an act of affection, done by placing a hand on another person's head, and either moving it from side to side gently (petting) or moving it up and down (patting). usually done with close and semi-close friends. can make one feel calmer and happier.
The mechanism in your brain that allows you to "play" songs in your head. Differs from an earworm in that the headpod is voluntary and plays songs that you like.