You know, this may actually qualify as a guilty pleasure. On the one hand, it's how my brain works. When a song I'm not familiar with comes into my head, my mind will abhor the vacuum of the missing piece and put something else in its place, and then I'll have a medley/mashup playing in my head like that. On the other, it's less obscure stuff, so much easier to recognize the constituent pieces, and also -- more earwormy.
I'll have to go back and listen to Girl Talk later, but I'm resuming this right after Knucks' show.