The act of drinking, AND driving at the same time.
"Dude, this guy is swerving
all over the place, he must be Multi-Tasking."
"I bet that fucker that got in a wreck
Beaux: "Nah man, let me have one more beer
before we leave."
Mcclintock: "Oh it's cool.. we'll just Multi-Task on the way there dude."
Driving While Intoxicated