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 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!"