Take a sip every time:

Lindsey has trouble with his prosthetic hand
Wesley gets smacked/insulted
Angel scowls
Angel doesn't show any facial expressions whatsoever (man are you gonna get DRUNK!)
David annoys you
You think, "wow, Doyle could have done that WAY funnier..."
Gunn freaks out
Kate's a bitch

Take a gulp every time:

Lilah makes fun of Lindsey because of his hand.
The team Doyle bets on loses miserably
The office explodes
David makes a million
Gunn's in an orange sweater
You think, "Wow, Doyle could have done that way cooler."
Dennis makes Wesley scream like a little girl
Kate's a super bitch

Drink the whole glass every time:

Wolfram and Hart ISN'T connected to this week's storyline.
The bookies call to collect
Angel sings
Wesley passes out
David shows up SANS purple cape and sword
Gunn makes Cordy go completely out of character (i.e. the convo near the end of "First Impressions")
You think, "Wow, Doyle better make an entrance or I'm going to pass out from boredom."
Kate surpasses Buffy in bitchyness

Drink the whole bottle every time:

Spike shows up (and/or kills Wesley in which case take 2 bottles and drink if you can keep from laughing long enough to down them...)
Dru is coherent and making sense.
Wesley gets killed
Angelus makes an appearance (and/or kills Wesley in which case take 2 bottles...)
Angel cries
Cordy is sweet
You think, "Doyle should come back and kick Wesley's ass just for THINKING that..."
David shows up and they LET him hang for a while.
Gunn screams like a girl because Dennis scares him.
Kate goes Janet Reno on everyone's ass.