Decisions a person makes(big or small) that are just categorically stupid.
Roommate A: 'Sorry roomy, I got a little drunk last light and spend the rent money on strippers.'
or
Person B: 'Guys I'm gonna come clean here, I voted for Bush'
or
Friend C: 'It's bad enough that you bought a Hyundai Lacey, but you just had to get one in big bird yellow. Those were some horrible life decisions, gotta tell ya.'