If you've spent much time on TinyTIM at all, then you've probably noticed the large numbers of very strange things that people say to each other, and that people say in response to them.
The most famous of these words is probably "foof." When someone says "foof," it's customary for everyone within earshot to respond with a rousing "yay." Why? Why? Why not? Why ask why? Just drink.
There are a few other word-response pairs that aren't as well known in these Latter Days of TIM (see: Latter Days): probably the most commonly heard of these are the "poof-gay" duality and the "vampires-fuckers" pair.
"Poof" used to be as well known as "foof"--it was even in the newbie adventure--but these days, it's been relegated to something that only real old-timers remember.
The 'vampires-fuckers' response probably evolved out of a great contempt for the growing number of MUSHes based off of White Wolf's Vampire:the Masquerade. Or maybe just contempt for the growing popularity of vampires in general. (Why people like damned creatures of the night... I'll never know. (Except for maybe Malkavians.))
To conclude, when people say "foof", say "yay."
When people say "poof", say "gay."
When people say "vampires", say "fuckers."