Phil Mickelson is known for his penchant for on-course gambling of all varieties and amounts almost as much as his pro success and major championships. Mickelson, reputedly, loves to put big money on almost every round, shot, hole that's not an official tournament round (and there's probably some money exchanged even then). At the Masters, he was heckled into a wager with a fan, which he lost and couldn't immediately pay because he doesn't carry small enough bills for that kind of game.
But that Mickelson gambling anecdote may have been trumped by this story from Paul Azinger, whose career overlapped with Phil's when the lefty was much younger and starting to make an impression. The two, along with Ben Crenshaw and Payne Stewart, were throwing wagers all over the place at Bay Hill, with new bets constantly put down as the ball was in the air. I'll let Azinger set it up, but it finishes with the now ESPN analyst with a Jesse Pinkman routine, telling Mickelson to "Putt it, bitch" and Phil responding as you might expect (via Matt Adams/SiriusXM PGA Tour Radio):
As Phil ages, and eventually retires, here's hoping a lot, lot more of these gambling stories come out.