A visual assessment one makes when determining if a minor
, typically an underage girl, is worth the risk of incarceration in exchange for an evening of debauchery.
Look at her through the fork, and if she still looks good through the 'bars', then it's worth the risk.
Man, that Hannah Montana is pretty hot. I'd hit that.
Dude! You know she's Jail Bait, right?
Nah, man. She totally passes the Fork Test.