Vapor

1. to be absentminded; forgetful;

2. a person not present; distracted;

3. to not show up or to vanish without explanation

1. "We missed the show because Jack totally vapored the tickets."
2. "Jack is such a vapor, always lost in this own world."
3. "Where's Jill?" "No idea, she just vapored."

Vapor Boy

A person who is not really there.

"Is that guy for real, or is he just a vapor boy?"