I honestly have always wondered this.
If I were an artist, I would probably forget where I was at one point. They go to so many cities while touring and it would definitely be hard keeping them all straight.
So, I can't really blame Brit Brit that while she was in Blackpool, England, she accidentally called them Birmingham. I know, I know, they're not even close to being the same city, but they do both start with a "B" so give the girl a break.
Check out the video of the flub below.