A Critter giggles or talks (not English, they're from outer space. Have you ever seen this movie?)
A Critter swears (curses if you're from that part of the country) unnecessarily.
A Critter turns into a ball and just starts cruising in ball-format. I don't know about you, but I think most pets would be WAY more terrifying if they traveled around in balls.
A fab as fuck space cop shows up (OK officially they're bounty hunters, but these fashion-forward space cops are so ready for Drag Race).
A Critter uses technology. Critters is often compared to Gremlins, but this isn't a fair comparison since Gremlins is a family fantasy movie and Critters is a scathing commentary on the lack of funding for the USA Space Program.
A Critter just doesn't give a fuck. Like eating a firecracker.
You see a Critter's legs (yes, they have legs and it's SO awesome whenever you see them).
FINISH YOUR BEER when a Critter "Critter rolls" into a toilet because it's on fire.
A Critter intimidates the little boy by knocking over his bike. WTF, Critter? Why you frontin'?
Bonus Drinks
Drink whenever you hear quaint 80's music and don't stop until it's over!
Drink whenever you see Billy Zane's bad ass rat-tail.
Rule #3 ("critter rolls") will roll you right into the grave!