Term for a driver or passenger of a car/truck/&c who, while there is music on the stereo, stomps loudly or crisply on the floor, keeping the beat in the absence of an actual bass speaker.
"Dude, you hear that? It's a Mexican subwoofer, man!"
"Your system is pretty sick, even with the Mexican subwoofer."
"You broke-ass bitch! When are you gonna get rid of the Mexican subwoofer?"
"This whip's pretty awesome, well, other than the Mexican subwoofer."