The son of a friend of mine once stuck a pinto bean up his nose, and didn't tell anybody about it until it came back out about a week after he'd done it. IIRC, he was four, also.
And Ears. Kids are amazing at getting stuff into small bodily orifices.
The following story was told to me by a co-worker; we were both in tears from laughing:
Her niece (age 4 or so) decided she wanted to take home the "adam's apple" from her cousin's "Operation" game, so she stuck it up her nose ... apparently it seemed like a really handy place to keep something hidden. No one knew about it at the time.
Later that night, at home, her dad playfully said "got your nose" and tried to grab it, and the little girl shrieked, "Don't touch my nose! I've got a toy in there!"
And for those who are curious, I believe they were able to get the apple out without too much trouble, fortunately.