"Bizz-Buzz" is a more challenging version of "Buzz" and would be a good activity for students who've already mastered that game.
The same rules of that game apply to "Bizz-Buzz," only this time, students will be given two numbers. When the group counts and one student reaches a multiple of the first number, they will say "bizz" instead. As in the first game, when a student reaches a multiple of the second number, they will say "buzz" instead. When a student reaches a common multiple of both numbers, they will say "bizz-buzz!"
For instance, let's say your target numbers are 4 and 7. When the group is going around counting, any student who is supposed to say 4, 8, 12, 16, etc. will say "bizz" instead of those numbers. If a student is supposed to say 7, 14, 21, etc. when it is their turn, they will say "buzz." The student who is supposed to say 28, however, should say "bizz-buzz."
Just like in the first game, if any student misses saying either "bizz," "buzz" or "bizz-buzz" at the correct time (or takes a long pause to figure out when they should say it), the entire group has to begin their counting over again with 1. Counting continues as long as students say the right numbers or terms.
As you can see, "Bizz-Buzz" is a good way to practice common multiples, mental math and cooperative learning. It may be difficult at first to keep up with the numbers mentally, but that's what makes it fun!
Give it a try and see how your class likes it!