A phrase used often in the canceled TV show "Arrested Development". The phrase is mostly used when the characters talk to themselves after a serious of poor choices/bad events. It's used to make light of bad situations, although the characters themselves don't find it funny.
MARTA: "I was really worried about you"
GOB: "You've got nothing to worry about. We're going to be together for a long time"
MARTA: "We're family now - I'm so happy. I'm going to call the kids!"
<MARTA walks out of room>
GOB: I've made a HUGE mistake