A fart that has been concealed within a briefcase for later usage.
When one unleashes the fart from its briefcase, the fart yells "FART" then smells unbearably horrible to unsuspecting victims (most frequently used on airplanes) ((often used by terrorists...pilots never see that shit coming)).
and that's what she said.
"You and me go together like two farts in a briefcase! :] "
"Random Airplane Passenger: WHAT IS THAT AWFUL SMELL?!
Man With Briefcase: THAT'S MY BRIEFCASE FART!
Random Airplane Passenger: Wow, that's nifty! I needta get me one of them that there briefcase farts! I can use it on my wife when she won't sex me up!"