Put on your birthday suit, wrap yourself in a blanket like a burrito, wait for your significant other, friends, or family (if you dare) to see you, and then quickly unwrap your butt-ass-naked-self in front of them, yelling, “Surprise!” You’re naked when you do this - in case you missed it.
Girl 1: Omg, when I got home, my boyfriend gave me a Birthday Burrito Surprise.
Girl 2: What the heck is that?
Girl 1: He was wrapped in a blanket, like a burrito, and then surprised me when he popped out naked!
when you are fucking your guy in the ass and then proceed to get another guy to unknowingly suck your dick post ass fuck
"Last night I fucked Mikey in the ass and then gave Andrew a burrito surprise."