Take one swallow if:

The date or time is 1013
The date or time is 1121
Mulder is called into Skinner’s office
Scully is called into Skinner’s office
One of the Agents draws their gun

Take two if:

Both agents are called into Skinner’s office
Both numbers (1013, 1121) show up in one episode
An alien shows up before the opening credits
An agent gets injured in the line of duty
Samantha is mentioned
They find a dead body

Take a shot if:

One or both agents are in the hospital
You hear a gunshot in the background
The shooter is rat-boy Alex Krycek
Someone actually gets shot
Mulder ditches Scully
BONUS: If Scully ditches Mulder, take a triple shot
They get sidetracked on an X-Files-related case
They smile lovingly at each other
Mulder kisses Scully in a non-sexual way (and vice-versa)
Skinner saves their asses

Take two if:

Both Agents have been shot
By each other
A contact dies and/or disappears
Someone’s family member dies
Mulder finds a bunch of alien bodies
Mulder or Scully sees a clone
One of the Agents “die”
One of the Agents gets abducted
Mulder and Scully are mistaken for a married couple
The tagline is different from “The Truth Is Out There”
Skinner and Scully have a face/off ("Drop your weapon!")
Mulder and Skinner have a face/off
Mulder’s paternity is questioned
Mulder is attempting to mix frozen OJ concentrate with Vodka

Take three if:

Mulder finds Samantha
Mulder punches Skinner
They lose the X-Files
Kersh sends them out to investigate manure piles
Mulder loses Samantha
Mulder tells Scully he loves her
They almost kiss
A strange fetishist kidnaps Scully
Mulder saves her in the nick of time
Scully saves Mulder in the nick of time
One of Mulder’s old girlfriends shows up
Scully gets jealous
Scully finds one of the tapes that aren’t Mulder’s
Mulder’s bedroom (or lack thereof) is mentioned
Scully tells Skinner to save his own ass
Someone comes onto Mulder
Someone comes on to Scully
My goodness, they really DO kiss!!!

Chug down a 40 and celebrate if:

They have sex
CSM is killed
Krycek becomes a good boy
Diana Fowley dies
Samantha is found
We finally know what the hell is going on

And for all you smokers out there:
Every time CSM lights up, so do you!