-A group of people containing mexican racial slurs in a confined area.
-A social gathering of Mexicans.
-Man Jeff your parties always turn out to be a beaner box.
-It smells like a beaner box in here
An old muscle car, (i.e. a Monte Carlo, Impala, Grand National) that is modified with hydraulics, ugly vinyl graphics and tacky gold rims that generally ruin the car's GOOD qualities.
Carlos: "Yo, check out my ride! It's a 1978 Monte Carlo with hydraulics, TIS rims, flame vinyl, a NOS tank by the console. It's beautiful!"
Any sensible person: "You just turned a good Monte Carlo into a crappy Beaner-Box."