Person A: I can't sleep, my nose is so congested.
Person B: Grab some vix, it should help.
Person A: i didn't even think of that, i'm going togive myself a vix sanchez and try catch a few more Z's.
Where feces is purposely smeared onto a persons upper lip, to resemble a thick mustache. Similar to mustaches worn by some Mexican men, hence the name Sanchez.
This has nothing to do with sex. Sex-advice columnist Dan Savage says the act is completely fictional as a sex act. Brian Bouldrey in Dirty Words: A Literary Encyclopedia of Sex says the act is an urban legend as it pertains to sex.
An amazing event! You screw your girlfriend from behind and then suddenly put your finger in her ass. Pull it back and give her a line of shit under her nose. Now she'll look like a Dirty Sanchez.