Tali, the 6-year-old I was hanging out with in Johannesburg taught me this Barney song:
"I hate you, you
Let's go out and kill Barney,
With a baseball bat and a 4 x 4,
No more purple dinosaur."
(sung to the tune of that irritating Barney song)
This is possibly one of the most disturbing songs I've learned from a child. And that's saying plenty because I know a lot of special (read: weird, highly-intelligent, funny) kids.