To muck around or be stupid.
Michael, stop fart-arseing around and mow the lawn.
by xXDaniiXx March 7, 2007
carrying out a series of small tasks while on the way out the door, delaying your departure. Fart arseing is often an infectious activity and can quickly spread across a group, severely undermining their ability to actually go anywhere.
Alex is really fart-arsing about now, that's going to make us so late...but actually while he's at it maybe I have time to redo my eyeliner.
by Bettibipbop July 6, 2017
polite way of calling someone an idiot, jerk, stupid, or inappropriately mean or stupid without sinking down into the usage of obscenities. Taken from the term arse for backside or bum and the word fart the sound that comes out when a person passes gas. Basically telling someone their comments are full of hot air and just trite, mean or silly.
E: Look at that bird in the sky!
A: There's no bird in the sky why are talking like an arse fart again?

Guy 1: Look at Jenni over there talking about Anna again and throwing salt.
Guy2: Yep that Jenni she keeps on acting like an arse fart.
by Sharky6 August 1, 2016