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
by carcassxcutter July 9, 2010
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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!"
by M-Chill December 22, 2012
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