That I would gain superior ninja powers by practicing dilligently throwing my two pronged compass thing from my maths set into a cardboard box target every night.
Gave that up on night two.
That I would stay on the #$&*^()%(* cabbage soup diet until I lost half my body weight.
Dropped out of that on day four
That I would stop masturbating if only God would save my friend from dying in hospital.
Lasted about a week. Which was tough - cause I had only just learned to do it. And trust me, as a guy, when you work out that X+Y= YIPPIE, you were refining your technique every chance you could get. A week turned out to be a very ... long ... time.
Any of you lads got violated vows as bad as that?