The girl is upside down with her head hanging off the bed/couch and she is giving the boy a blowjob. When he cums she keeps it in her mouth and proceeds to spray it all over his body, hence the topping on the cake.
Boy1: dude, why are you all sticky?
Boy2: girlfriend tried something new, the upside down pineapple cake!
Boy1: you need to end that relationship asap.
Boy2: girlfriend tried something new, the upside down pineapple cake!
Boy1: you need to end that relationship asap.
by angelD2010 March 8, 2009

by THe king of cunt November 9, 2009

Tom - "That chick is god awful ugly bro!"
Jake - "Yeah, she's got like...backflip upside down syndrome!"
Jake - "Yeah, she's got like...backflip upside down syndrome!"
by dczech October 18, 2008

its like the game you would play as a kid: wheelbarrow races. when the guy stands upright and the girl would be the wheelbarrow but with this position, she is facing him and they would fuck just like that.
"...yea i was the gardener and she was the wheelbarrow but i got to see her face as i fucked her because we did the upside down wheelbarrow position."
by PinkBunnyLove July 29, 2009

The act of a regular fist bump, yet the fist is upside-down. This kind of fist bump is a rejection of the purpose of the fist bump, yet must be done for the purpose to fit in.
Ted: Dude, I just totally busted that wimp in the face
Victim's Friend: Oh, yeah man
Ted: (Requests a fist bump)
Victim's Friend: (Uses an Upside-Down Fist Bump)
Victim's Friend: Oh, yeah man
Ted: (Requests a fist bump)
Victim's Friend: (Uses an Upside-Down Fist Bump)
by LexxiFoxxx June 8, 2011

Down for butt stuff
by Kelsodilla January 30, 2016

Upside down smiley face is when a girl upside down doing oral and gets a ticklish feeling on her nose from a mans gentelia, thensmiles which brings that forward.
by Helpmecreatethenewlingo January 18, 2016
