A Tijuana Taco is the turned-up or folded-up bill of a baseball cap being worn by anyone that is used (almost exclusively by the filthy fucking mexican) as the perfect temporary storage device for their taco when they are taking a shit.
Oh mang, i reelee got to take a cheet but eef i poot down my deeleeshees taco somebodies ees going to steels eet. Wait a meenit, i done haves to poot eet down i can juss poot eet heer on dee tops of my deesgusteen bazeball cap dat ees so conbeeneeinly locadid on my greesee, feelthee head seence i already have dee reem of my cap foldeed up like dee tijuana taco my mother teech mee to make !! ...ALL ACCENTS USED IN THIS EXAMPLE WERE TRANSLATED VERY CAREFULLY FROM ENGLISH TO BEANER BY A REAL AMERICAN OTHERWISE KNOWN AS A WHITE MAN, SO PLEASE REMEMBER TO USE THE PROPER DUMB-ASS BEANER ACCENT WHEN READING, OR, IF YOU ARE ALSO A WHITE PERSON, LIKE ME, JUST PRETEND THAT YOU ARE RETARDED.
Tijuana Taco is when you take a crap and place it under a cars visor (Hence the term taco) of a very unexpecting person. So when He/She is driving and opens the visor it falls on their lap. Hopfully not causing an accident so the driver and gifter get a good Laugh from it.
When during sexual intercourse a man takes lettuce, shredded cheese, and taco sauce, and then covers the woman's vagina in said ingredients. The man then proceeds to perform cunnilingus on the woman whilst eating the additional ingredients.
Joey-so what did you end up doing with sarah last night?
Ian-well she likes new things so i gave her the ole Tijuana Taco.