When you are driving and stuck behind some a-hole going under the speed limit and have another a-hole tailgating you. Unfortunately, by being in the middle of this, means you too are a douchebag.
When a sports team loses Game 1 of a playoff series but wins the next four. Usually gives the opponent a sense of hope (especially if Game 1 was an upset loss), but then they take them right back down to Earth, a “douchebag” move.
The 2001 NBA Finals started out by the 76ers getting a huge upset win in LA, but the Lakers completed the douchebagsweep by winning the next four, and thus the championship.