After 1647 meals in a row where Charlie (Charlie Sheen, above right) has picked up the cheque, Alan (Jon Cryer, above centre) finally cracks open his wallet.
It's such an event that the family stops in their tracks. Is he dying? Is he ill? When the truth comes out, it's stranger than anyone suspected.
It seems he's branched out with his chiropractic business, offering "in-house therapy" to select clients. Or to be more accurate, massage with a "happy ending" for a rich widow.
While Charlie has a parallel storyline here about sleeping with his ex-girlfriend's best friend while still trying to get his old relationship back on track, it's definitely Alan's downfall that makes this an above-average episode.
Years of living on high moral ground give him a lot further to fall and he lands with a hilarious crash.