It is when you get head (blow jobs), for the rest of your life from someone. It usually comes up from a crazy bet to win a football game or something else stupid.
Bristol: we are going to lose
Pat: no we're gonna win.
Bristol: ...we re gonna lose
Pat: okay well if we win then you owe me head for life, and if we lose then ill buy 50 cheeseburgers from McDonalds.
Bristol: okay fine
20 min later and after the team wins
Pat: haha hell yeah