Per the original request of the thread, I learned this as a particularly crude (and not particularly witty) rugby song. Assuming there's no one faint-of-heart on this thread, two of the lead lines I remember were :

aye aye ya aye/Your mother licks bat sh!t off cave walls
aye aye ya aye/Your sister goes out with sailors (or replace "sailors" with the two syllable nickname of a friend your looking to embarrass)

I'm quite certain "Your father" and "Your brother" did things as well, (I think cucumbers were somehow involved) but it's been a few years since I've heard this ditty...and since I wasn't actually on the rugby team, I didn't commit it to memory.

Peter