when a man inserts a fly into his urethra before performing sexual acts upon vagina, quickly pulling out and then sticking in the anus when about to ejaculate, releasing the fly into woman's asshole projecting the fly throughout her body and out her mouth. (successful if fly remains alive).
The male prostitute performed the infamous "mexican horse fly" on a very satisfied customer.
by chives4u5647 November 8, 2010
Get the mexican horse fly mug.