When Eric invites Mitch to join the kids in the basement:
Hyde: Forman, why’d you invite him over? You were almost out of there, and you turned back around.
Kelso: There’s only two times in life that you turn back around: basketball and runway modelling.
Fez: No, and square dancing. It’s called a do-si-do.
Season 6, Episode 19
The funny/sad part is that you don’t turn around in a do-si-do…