A Filet Mignon is the sexual act of performing oral sex
until the male genitalia goes from a soft boner to a "semi-hard" dick
then sticking the penis in the vagina until it becomes hard. The act got its name because the filet mignon cut of beef is known for being the most tender, like a soft penis.
Bro, Chelsey couldn't get my dick hard last night, so we filet mignoned until i was hard enough to blow my load.