The many uses of WD-40

The many uses of WD-40 include;

Protects silver from tarnishing
Cleans and lubricates guitar strings
Gets oil spots off concrete driveways
Gives floors that 'just-waxed' sheen without making it slippery
Keeps flies off cows
Restores and cleans chalkboards
Removes lipstick stains
Loosens stubborn zippers
Untangles jewelry chains
Removes stains from stainless steel sinks
Removes dirt and grime from the barbecue grill
Keeps ceramic & terra cotta garden pots from oxidizing
Removes tomato stains from clothing
Keeps glass shower doors free of water spots
Camouflages scratches in ceramic and marble floors
Keeps scissors working smoothly
Lubricates noisy door hinges on vehicles and doors in homes
Gives a children's play gym slide a shine for a super fast slide
Lubricates gear shift and mower-deck lever for ease of handling on riding mowers
Rids rocking chairs and swings of squeaky noises
Lubricates tracks in sticking home windows and makes them easier to open
Spraying an umbrella stem makes it easier to open and close
Restores and cleans padded leather dashboards and vinyl bumpers
Restores and cleans roof racks on vehicles
Lubricates and stops squeaks in electric fans
Lubricates wheel sprockets on tricycles, wagons and bicycles for easy handling
Lubricates fan belts on washers and dryers and keeps them running smoothly
Keeps rust from forming on saws and saw blades, and other tools
Removes splattered grease on stove
Keeps bathroom mirror from fogging
Lubricates prosthetic limbs
Keeps pigeons off the balcony (they hate the smell)
Removes all traces of duct tape
Some folks spray it on their arms, hands, and knees to relieve arthritis pain.
The favorite use in the state of New York: WD-40 protects the Statue of Liberty from the elements.
WD-40 attracts fish. Spray a LITTLE on live bait or lures and you will be catching the big one in no time. It's a lot cheaper than the chemical attractants that are made for just that purpose. Keep in mind though, using some chemical laced baits or lures for fishing is not allowed in some states.
Keeps away chiggers on the kids
Use it for fire ant bites. It takes the sting away immediately, and stops the itch.
WD-40 is great for removing crayon from walls. Spray on the mark and wipe with a clean rag.
Also, if you've discovered that you have washed and dried a tube of lipstick with a load of laundry, saturate the lipstick spots with WD-40 and re-wash. Presto! Lipstick is gone!
If you sprayed WD-40 on the distributor cap, it would displace the moisture and allow the car to start. (If I knew what a distributor cap was, it might help)
WD-40, long known for its ability to remove leftover tape smunges (sticky label tape), is also a lovely perfume and air freshener! Sprayed liberally on every hinge in the house, it leaves that distinctive clean fresh scent for up to two days!
Seriously though, it removes black scuff marks from the kitchen floor! Use WD-40 for those nasty tar and scuff marks on flooring. It doesn't seem to harm the finish and you won't have to scrub nearly as hard to get them off. Just remember to open some windows if you have a lot of marks.
Bug guts will eat away the finish on your car if not removed quickly! Use WD-40!

Cyclist here. Do NOT use the WD 40 on bike parts. It's a very thin lube that will quickly evaporate or be chased out by water, leaving you with no lube. In fact, even if you have good oil on your chain, the WD 40 will chase out that oil, leaving the chain even more susceptible to water and dirt damage. Skateboarder here. Don't use WD 40 on your bearings for the same reason. If you wanna clean your shit maybe you can use it to clean them, but then you will want to add some decent lube like speed cream to keep em rolling fast. It attacks rubber and plastic, there are far superior lubricants and adhesive removers than WD-40. I use Triflow oil for everything I used to use WD-40 for before I learned better. Is the WD-40 marketing team in full effect on Reddit lately? I don't get this whole thing where WD-40 has been elevated to the useful status of duct tape. 3-in-1 oil is a vastly superior lubricant and can be had anywhere for cheap.

I also want to gut all the ass holes who use it on fishing lures. Mayonnaise removes adhesives. Want to get rid of a bumper sticker? Smear a generous glop of mayo on it and around the edges. Wait overnight. Peels off clean. This message brought to you by the American Mayonnaise Council, and the letter "K". WD-40 has it's uses and can temporarily break things like car door hinges free, but it is NOT a lubricant. If you want to keep car door hinges working properly, use a proper lubricating fluid that you should find at an auto parts store. Only a real lubricant should be used on hinges, pivots, locks, bike parts, or whatever you want to keep moving smoothly.

Uh, no. Don't do this. There are enough chemicals floating around in our waterways without idiots adding WD-40 to the mix. Keeps flies off cows Keeps away chiggers on the kids I wouldn't do either of these, either. If you look at the MSDS for WD-40 it really doesn't sound like the kind of thing I'd want to spray on animals or children.

WD-40 is relatively safe, and you're correct that the MSDS says so, but just because the MSDS indicates that skin irritation is unlikely doesn't mean it's a good idea to spray it on your skin. And if you're spraying it on a child or an animal it's a bit difficult to prevent them from inhaling the fumes.

There are far safer alternatives to keep flies off of cows, such as fly sprays designed specifically for that purpose. Same goes for chiggers and kids. I just don't see the benefit of using a chemical for an unintended purpose that could cause a bad reaction (no matter how remote) versus using a product that's more specifically designed for that purpose.

From the MSDS: SKIN: Prolonged and/or repeated contact may produce mild irritation and defatting with possible dermatitis

That's exactly the same thing that will happen if you keep a zippo in your pocket, actually. Lighter fluid does that too. Doesnt seem too bad, honestly.

And as far as chemicals in the water goes, the drop of WD-40 is going to do far far far far far less damage than the splash of gasoline that leaks into the water from the boat engine, or even the exhaust from the engine itself. Many plastic lures are coated in oil before they're packed anyhow to keep them from sticking to themselves.

But if someone told you to use lighter fluid as a bug repellant (when there are actual bug repellants available) would you do it? I want to re-state I'm not saying that WD-40 is this hugely dangerous product that will make your skin peel off, and lord knows products such as nail polish remover are far more dangerous, but why would you use it on a child or animal if there are other products specifically designed for that purpose?

With respect to your comment about WD-40 versus the other pollutants, I agree that the harm is probably minimal, but again, why would you do that for no reason? Why use WD-40 when there are chemical fish attractants available that are safer for sensitive aquatic ecosystems?

I'm actually not sure they are safer.. I doubt the recreational fishing industry is tightly regulated regarding that kind of thing. Its predominantly regulated by local fish commission laws.

Also, chemical fish attractants are expensive. Also, real men don't use fish attractants at all. They're for people who suck at fishing. :) WD-40 does not loosen stubborn zippers. Last night I took the hot waitress from Chili's out for the fourth time. I gave her four shots of WD-40 with mint and an orange twist, and I still didn't get laid. As someone who worked in a quite angsty pub with a coked up clientele, you have enough people threatening to beat the shit out of you working behind a busy bar without Bolivian marching powder thrown into the equation. These properties make the product useful in both home and commercial fields; lubricating and loosening joints and hinges, removing dirt and residue, and extricating stuck screws and bolts are common usages. The product also may be useful in displacing moisture, as this is its original purpose and design intent.

It does lubricate. Water does not need to be present. The original purpose was for water displacement but it is commonly used as a lubracant.
That's like saying corn isn't food, it's a seed. Yes, it was originally designed as a seed but is commonly used as a food source.
Edit: Downvotes? Seriously guys? It is a lubricant. It's not a good lubricant, but it does lubricate. It contains mineral oil which is a lubricant.
In fact, it doesn't do a very good job at many of it's uses, many of which are in the OPs list.