Fanny Flush is the act of urinating inside a lady's vagina until she overflows and then pushing your fingers into her vagina causing the urine to spill over and out of her vagina and onto the ground.

(Think of it as putting an ice cube in a full glass of water and the water spilling over onto the table - this is the same kind of thing.)
"I gave her a fanny flush last night."

fanny flush sex urine
by Bartron2291 August 26, 2009
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