(or caffeine-buzzed, for those under 21 :P )

Take 1 sip if
Kagome yells "Inuyasha!"
Inuyasha yells "Kagome!"
Naraku says "Kukuku"
any character narrates the action
Naraku escapes a fight

Take 2 sips if
someone other than Kagome yells "Inuyasha!"
Someone other than Inuyasha yells "Kagome/-sama/-chan!"
Inuyasha uses Kaze no Kizu
they're fighting a one-shot monster
Miroku is poisoned or interrupted due to threat of poison
Kagome gets jealous of Kikyou
Miroku flirts with other women
Ginta and Hakkaku yell, "Wait for us, Kouga!"
Jaken says, "Wait for me, Sesshoumaru-sama!"
Kohaku angsts
Inuyasha gets a sword upgrade
Sesshoumaru angsts about his sword

Take 3 sips if
Sesshoumaru fights bare-handed
Inuyasha fights bare-handed
Kagome does something effective in a battle
someone other than Inuyasha kills something
Naraku creates a new detachment

Chug if
a recurring male character dies
Shippou defeats the monster of the day
a character actually matures enough to lose an old habit