Back 2 Back can be a mixer if your group is small enough or it can be a group game if you have a group of 30+.

Supplies:

Nothin'

How to Play:

Basically all you do is have two students sit on the floor back to back and they have to stand up without putting their hands on the floor. Then, if they do it succesfully... add one more person to the group. If you do that successfully, add one more. And so on and so forth.

If you want to watch a video for an example, click here.

Pro Tips:

This game could take some time if you have a large group. Plan for a potentially 10 minute game.
Keep it as fast paced and energetic as possible.
Make up a youth group record and challenge them to beat it. "The record is 28, how many people can we get?"