Uncle Slam 

When a female sits on a mans penis facing away from him while he puts lit sparklers in her her vagina while he waves small american flags in his hands; sex position specifically supposed to be performed on 4th of july.

My wifes vagina got destroyed last 4th of july from when we Uncle Slammed

Uncle Slam by carcassxcutter July 10, 2010

Uncle Sam Slam 

When two individuals have sexual intercourse in the cowgirl position at the base of the Lincoln Memorial while waving several American flags.

"Nothin' says God Bless America like a good ole Uncle Sam Slam!"

Uncle Sam Slam by M-Chill December 21, 2012

I'll slam ya uncle 

Trash talk used to imply that you're more skilled than someone. Like saying that you can beat your challenger and their uncle.

Person 1: You tryna ball?
Person 2: Bruh, don't... do not do it to yourself.
Person 1: What??
Person 2: Bro, I'll slam ya uncle!

I'll slam ya uncle by XenoXndr May 15, 2017