The act of drinking alcohol specifically to be able to sleep in an uncomfortable place. Typically used outdoors, when sleeping in the front seat of a car, or when sleeping on the floor of your friends dorm.
Kieth: Hey Bud, wanna come camping at the rock quary this weekend?

Me: Sure, do I need to bring anything special?

Kieth: Bring an air mattress, the ground is rocky.

Me: I'll be fine, I plan on bringing my Beer Mattress!
by dee-rock May 16, 2010
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