> So we walk up to them, and I said, "HEY guys!
> Remember me? We met last week at...that party!"
> and the other girls said similar things to the
> other guys.

There's your problem right there. You gave them a time frame that they could easily remember! Of course they knew you were pulling some kind of prank; they probably didn't even go to a party last week and even if they did, it's recent enough that they can remember who they met and who they didn't. Next time, try this:

"HEY guys! Remember me? From that [party or other event] last year?"

or, just address one of them with something like:

"HEY! Remember me? From FOURTH GRADE! Man, it's been so long!"

This way, there may be some doubt, but their memory of times that far back may be fuzzy enough that you can bluff your way through an entire conversation!

Anyone ever had the guts to try this?

Gri"I mean besides Sam, for whom it backfired"shny