If you guessed this is what my son stuck up his nose to gross out his sister, you'd be correct!
(Yes I did give him a lecture about sticking things up his nose from a safety perspective.)
Update: Putting my son to bed last night, I asked him, "What are you allowed to put up your nose?" The correct answer, of course, was nothing. He answered me very seriously. "Mom," he said, "there are two things that go up your nose; air and boogers." I stand corrected.