Actually "Hoarfrost" is the song I force into my head when I can't sleep because of persistent, stupid thiughts filling my noggin, or when I have an absolute shit song stuck in there. So I guess it doesn't really fall into my head naturally. I've been using it as a cognitive sedative and earworm cure for years and years, so I've probably trained my brain to have it on deck.
It's great though. Such a calming song, but also dynamic and interesting enough, with enough different moving parts, to hold my attention. Plus it's one of my all time favorite Sonic Youth songs.
Aside from that, I tend to get "Tom Violence" stuck in my head quite a bit.