carpool bandwagon

Your team is having a garbage season, so you resort to cheering for someone else's team that you know.

Girl: I hope atlanta wins.

Guy: But you're a Titans fan... Don't front, especially not because they suck this year.

Girl: Yeah but my dad's a Falocons fan and my roots are in GA!
Guy: That may work in soap operas, but in the sports world you're just pullin a carpool bandwagon. Disallowed...