Concentration 64 goes like this:

Concentration (clap clap clap)
64 (clap clap clap)
No repeats (clap clap clap)
Or hesitation (clap clap clap)
I'll go first (clap clap clap)
You go second (clap clap clap Repeat as necessery number of persons
Category is (clap clap clap)
----- We usually use names or animals
I recently played this at a camp in Alabama. I'm 12