When three people sit in the back seat of a car, and a fourth lays across all three of their laps. The person laying is the Mexican Seatbelt, and calls "Mexican Seatbelt" upon assuming this position.
"MEXICAN SEATBELT"

"Dude, your elbow is crushing my balls"
by THCidiot July 7, 2009
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A Mexican seatbelt is a rope that keeps someone secure while riding in the back of a truck.
Passenger: I'm surprised Justin didn't fly out of the bed on that last speed bump.
Driver: It's cool, he's got a Mexican seatbelt.
by DBnick May 5, 2007
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