Adjective. Occurs when you cut a fart, but instead shit yourself. Similar to a "Shart", however, a fart steak has a definite form.
I'd love to walk over and see you from my present location, but I just made a fart steak in my pants.
The visible panty line that is formed on the backside of a pair of fullback (granny) panties by the gusset stitching, going from one butt cheek to the other.
Oh man, every time that Nancy bends over when in her yoga pants, you can see her bumstache!