The act of starting at one end of a person-filled room, ripping a nasty fart (the "thick" ones are better, as they cling more), then moving briskly to the other end of the room, staying ahead of your own stench, yet "dusting" the rest of the room with your flatulence.
wes decided to cropdust the entire back half of the apartment, so he walked from the laundry room through the living room into the bedroom, all the while farting and pulling the smell with him.
The act of farting while walking past others, leaving them to gag in the wake of your shit-smelling foulness. Can also be referred to as the airdrop.
Ron: "So there I was just typing away at my desk, then I smelled it....that wretched odor that could only be caused by someone cropdusting."
Jim: "Oh man I've smelled that before! I think it's that new foreign girl Yun Li. She pulled an airdrop over at my desk the other day, and I threw up in my mouth a little."