Heeeee! Crossover zombies of stupid-making! That's hilarious ... it reminds me a little bit of that scene in "Blazing Saddles" (have you seen that?) when the characters break the fourth wall and start rampaging through other movie sets. In fact, Moronium Oxide is very useful for explaining all sorts of lousy plot decisions! *g*

I'm pretty sure I haven't seen that episode of Buffy -- I saw all (or at least most) of the first four seasons, didn't see the fifth at all, and saw bits and pieces of the sixth and then all of the seventh ... and somewhere in there, I appear to have missed it. But I've heard it mentioned before and it sounds like it was one of the best eps.