When I started using the class-yes, it was during my first year of teaching after a short presentation (less than 15 minutes) from another teacher (from another school) who had been using a thing called "power teaching" and I didn't get a clear understanding of it, so I began using variations right away... I had four classes as a language arts teacher and had each class vote on their own suggestions.
I of course, had ultimate call on ones that I just couldn't bare to say like "hillshire farms: go meat" (Although one class this year convinced me to do "Subway:Eat fresh")
Some I had last year were hamburger:french fries, lolly:pop, hey:what (my GATE kiddos loved that one

)
But when I started this year, I kept class:yes until about the middle of the year, when after I noticed bullying issues arising, each block/homeroom period came up with their own team name and mission statements.
Based on their team "theme", we all brainstormed ideas for the class part and the yes part, then the mighty oh yea as well.
One class, called the Hot Chilies, respond to my "Chile!" with "Peppers!" and when they get a point they say "Ole!" (o-lay)
Variations can be so fun and add variety to the class yes because the students can get bored and sloppy with class-yes, and since I didn't really have the rest of the scoreboard strategies in my repertoire (like the practice cards and guff counter) variations on he class-yes can extend the use of the scoreboard/class-yes so you can ensure your back pocket stays big and full through the rest of the year.
I can't wait until next school year to implement all the strategies in the correct order! (plus I've been told its a "difficult class" coming my way so I'm looking forward to having these great tools to use in tough times.