If you can’t beat them, join them
Sports fans can be very creative when it comes to songs, slogans and signs, but often they just say whatever others say about their team. This guy, for example, had enough of people saying Boise wasn’t even a state, and he decided to point out that perhaps they aren’t but so are a lot of other teams.
It might not be vert creative, but it gets the message across. So what if Boise even a state? When you think about it, it’s not that good a burn, as it doesn’t reflect anything about their skills.