A person who is poking along in traffic or driving erratically because he/she is yaking on their cell phone.
That person who is holding up traffic while talking on the cell phone is a real yakass.
yakass: define #2
the ass of a yak; similar to jackass, but instead it refers to the goat-like creature; when a foreigner tries to say jackass, but they’re J’s sound like Y’s
“Did u see Dave running down the street after his pants were taken by the gypsy? Man what a yak ass, homes!” excaimed Juarez.
yakass: define #3
excellent alternative to jackass. Nobody wants to be a yakass.
Man, the boss owns ur ass. You are such a yakass.