A sexual accident which occurs when someone is performing cunnilingus on a female from the Baja region of Mexico. The female farts, which subsequently becomes a shart and the male ingests a portion of the stick suprise, much to his pleasure.
Hey dude, I had a delicious San Diego Shit Sandwich from Rosalita last night.
A sexual experience with a hispanic female in intestinal distress
When you're eating out a mexican from Tijuana and she let's loose a fart, which actually winds up being a shart and you ingest some of the sticky suprise, now that's a San Diego Shit Sandwich