Comedy.
I was sitting on the bus and two young children--brother and sister--got on with their nanny. The children looked to be about 5 or 6 and each has a paper airplane. I was already sensing a bit of tension between them--the I'm-annoyed-with-you-sibling tension. And sure enough, a few minutes later when the little girl's airplane fell to the ground, the little boy picked it up, promptly eliciting a very strong (and slightly drawn out for effect), "NOooo!" from his sister. She then proceeded to take the airplane from him, place it back on the ground and then make a point of picking it up herself. I hadn't been prepared for that reaction. And so I laughed.