Common courtesy tips of the day...you're welcome! :)
1.) If you're 6 feet tall, don't stand in the front row of a Zumba (insert any kind of aerobics class here) class.
2.) Don't come in late to the class and then ask someone to move, try to create your own front row or stand directly in front of someone. Windows, people, WINDOWS!
3.) Don't say "I feel fat" when you're clearly NOT the fattest one in the room.
4.) Don't say "I thought you were younger/older than you are!"
Both are offensive. When you're young you want to be thought older and when you get older you want to be thought young. How 'bout a little DADT here, huh?
5.) Don't ever tell someone to "Eat a sandwich"
I see this all, happening all over, all the time. Let's knock it off already!