What do I tell a girl when she says "tell me something interesting"?

It shouldn't be necessarily my girlfriend. However, sometimes in the middle of a talk, a girl throws the phrase, "tell me something interesting". At that moment I feel as if I was struck by lightning: absolutely taken aback and at a loss for words. Then, an awkward silence comes. I read a lot, but at that moment I feel as if a tumbleweed was rolling through my deserted mind. Please, help me with ideas.