When you have sex in the dark with a girl that thinks you're a different person but you aren't aware she mistook you until after the deed is done.
"How'd you lose your virginity?"
"Oh, I pulled a Casper The Friendly Ghost, once I realized she mistook me for someone else I got the hell out of there!"
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.