It is "zipper" that is the contraction. The correct designation of the object is "zip fastener".

I recollect perfectly well from my "prep" (UK speak for private school usually boarding for chilren up to the age of 13) school and my public school (I assume everyone now knowns that bit of UK speak) both pupil/pupil and pupil/master homosexual interaction. I also recollect insulting terms usually used in those contexts - usually "queer" - but I don't recollect any "playground rhymes" using homophobic insults. In fact I don't recollect any "playground rhymes" at all - maybe they are more common amongst girls?

Where I am wholly clear however is that the first time I heard "gay" as a generally unfavourable quality descriptor was only a few years ago, when a friend of mine with a rock band, and himself rather keen on Marshall full stacks, referred to another guitarist's rather nice Fender Twin Reverb as a "gay-sounding Fender Amp".

In that context and every one since in which I have hear that usage of "gay" as meaning "inferior" I am wholly clear that it was analogous to describing homosexuality as inferior to heterosexuality. I have had a few arguemnts on the point since with would be hard rock heroes who get quite upset about being pulled up on PC grounds!