On a multi-lane road (usually a highway or mainstreet), lane drifting is when a car suddenly begins 'drifting' over
the lanes, usually because the driver isn't paying attention, or cannot see the lanes because they aren't painted well enough.
Usually they'll
hover between two lanes, going the
speed limit, and holding up traffic in both lanes.
I was stuck going
65 because the guy infront of me was lane drifting between the left lane and center lane, and was apparently oblivious to the chorus of car
horns being
layed upon him.