Doin' a Twinkle
This is when a person disappears without telling anybody where they are going and for how long. The person doing a twinkle either is found completely oblivious that they are "missing" or they return as stealthily as when they left
Person 1: Dude where did Bernie go?
Person 2: I don't know, I didn't see him go, he's doin' a Twinkle
Person 2: I don't know, I didn't see him go, he's doin' a Twinkle