Fart Residue
residue built up from repeatedly farting on any type of object consisting of fabric (clothes, seats, blankets, etc) this leaves a heavy scent of fart in the affected areas
After eating Indian food, I had a massive amount of fart residue in my boxers
Fart Residue
The soaked in, gelatinous remains on your underwear after a very hot and wet fart.
Aw man, I got fart residue on my underpants.