The act of either jerking off or receiving a traditional hand job at the beach,or a place with comparably sandy conditions. This is in reference to the general sandy and unclean conditions associated with Mexico and select parts of the south western united states. Without this clarification, it is assumed the hand job is without sandy discomfort in its original form.
Bro -"Hey Jim did you get any action with that chick?"
Jim -"Yeah dude, we went to the beach and I got a hand job!"
Bro -"Man, I am really sorry to hear that. Thats called a Mexican hand job."
Jim -"I'm still pretty raw..."
When a woman wraps your wang in a burrito or soft shell taco and procedes to jerk you insanely until you spooge into a crunchy chicken chalupa.
Ernesto: Yo, that whack bitch wouldn't give me a mexican handjob so I gave her a mexican avalanche
Umberto: Fuck that shit homie, you still work at Taco Bell?
Ernesto: Nah bitch, I got fired for shooting my jizz load in the sour cream!
Umberto: Playa you trippin!