normally just hands doing seperate things such as shutting the fridge whilst opening the microwave.
can be used as a cover when doing something your not supposed to. eg. grabbing another beer and squeezing a girls ass. when she turns around you can claim it was you because you were getn another beer.
"bro semi task for me and put this on the barbie while u turn the steaks"
Paying distracted attention to three things for fifteen minutes doesn't equal full attention for five minutes to each of three things.
Semitasking gives the illusion of versatility and a sense of accomplishment without the results of either.