Variation of "Dirty Sanchez"
Taken from drug dealers in San Francisco's Mission district in the 80's-90's, who would show drugs for sale and then snatch they money offered and run away.
One drug Dealer in particular, a street musician, had the street nickname "happy Sanchez' due to the fact that he smiled and was super friendly before, during and after.
He would play guitar, sing, offer drugs and then take off after money was handed to him
"he pulled a Happy on me"
"Lawyers are worse than a happy Sanchez"
"happy Sanchez!" (said when grabbing something from someone and running away. now popular in San Francisco public schools)