It's a small thing, but a friend and I were having coffee in a park, and he offered me the rest of his muffin, since he was full. I didn't really want it, and we looked guiltily at it for a bit before spiking it into the garbage can, yelling "Take that, Sunk Cost Fallacy!" and doing a brief high five/victory dance.

It's nice to have a social network that gives you positive feedback for spotting and short-circuiting biases.