It depends on what type of dancing. If you mean slow dance, if you are a girl you put your hands behind the guys neck, if your a guy you put your hands on the girls waist. If you mean just dancing to...
Just dress like you are going to a party. Girls should dress modestly (Modest is hottest!) Same for you guys. Dont wear heavy clothing because It could get very hot very fast.
I have been in the same problem i have found some though here they are: Night club Hawaiian urkel and ugly Betty Halloween Hillbilly Michael Jackson and Beyonce Knowels 7. dancing nerds
You could do Mardi Gras/masquerade with masks, winter wonderland where you have to wear white, summer, or even Las Vegas could do a denim theme, a 60's dance, or a midnight dream, with all black.