Twelving Edit Meaning

1.

To stand a motorcycle or other vehicle straight up in the air, front over back.

In motorcycle stunting, pulling a wheelie so high that the bike rests on the it's tail section is called a "twelve o'clock". The act thereof is called "twelving".

See wheelie, stunting

2.

To 'space out'. Specifically the special sort of mental sluggishness brought on by watching television or any similar mental haze.

1: "Which street do we turn onto?"

2: "Huh? Oh, sorry. I don't know. I must have been twelving."

See spacing, spaced out, spacing out, haze, fog, foolish, attention, groggy