Because he knows where all the naughty girls live.
When he found out, Santa shouldn't have gotten mad, he only had his elf to blame. Now Santa won't forgive him until elf freezes over.
I told you it would rain, dear.
Everybody I don't know. All over the planet I guess.
If you know that one, try this one: Why do seagulls fly to the dump
ATP
Manhatin'
He knows where all the naughty girls live. I actually heard this in the video game LA Noire. Thought it was pretty funny so I bust it out every Christmas.