As I drove home from the vet's a little while ago with the cats singing a duet of post-shots protest in stereo (one in the back seat, one in the front), I heard something on the radio that made me blush for shame at my own ignorance. Apparently 'drop kick', when used as a noun, is rhyming slang for, well, you know.
I'd always thought it was a particular kind of figure of speech (and I'm sure there's a name for it in classical rhetoric, but I am too lazy to look it up), referring to what one would like to do to the person in question. Whenever I've called someone a drop kick in the past, I've had this very satisfying mental picture of dropping them onto my sturdy boot and punting them out into the traffic. Whenever I say it in future, all I'll have a mental picture of is, well, you know.