The only possible explanation for all the loud booming that comes from a low rider car. There must be a Mexican in the trunk with a bass drum.
El Bajito Loco drives up and down the street with a Mexican in the trunk with a bass drum. The Mexican keeps beating on that drum, perhaps to let everyone know he's in there.
Refers to the sounds trunks make when they have subs in them, as if Jackie Chan is in the trunk doing karate inside. Came from the Young Dro song "Man In The Trunk".
"That bass is bumpin'...what you got in the trunk?"