Pint of no return

The point while eating a pint of ice cream after which the only reasonable course of action is to finish the entire pint of ice cream and feel like a pig rather than putting the remaining ice cream back in the freezer

Susan had only wanted to eat a single serving of Ben & Jerry's Chocolate Fudge Brownie ice cream with her late-night Gilmore Girls marathon, but unable to stop herself, she soon crossed the pint of no return.