Question: I was trying to make my character do wave in air but the mesh seems to fall off everytime.
I cannot identify the problem. See the images.
[![image1](https://i.stack.imgur.com/vr635.jpg)](https://i.stack.imgur.com/vr635.jpg)

[![image2](https://i.stack.imgur.com/mcsT4.jpg)](https://i.stack.imgur.com/mcsT4.jpg)

[![image3](https://i.stack.imgur.com/9c2dR.jpg)](https://i.stack.imgur.com/9c2dR.jpg)

[![image4](https://i.stack.imgur.com/5rGVE.jpg)](https://i.stack.imgur.com/5rGVE.jpg)

[![](https://blend-exchange.giantcowfilms.com/embedImage.png?bid=8sSdPJBm)](https://blend-exchange.giantcowfilms.com/b/8sSdPJBm/)

Answer: 
You need to change the *IK Pole Angles* to -90° so that it doesn't deform your mesh:

[![enter image description here](https://i.stack.imgur.com/Ie2W2.jpg)](https://i.stack.imgur.com/Ie2W2.jpg)

Also you need to change the modifiers stack, this seems to be more logical (and enable the *Armature* modifier's *Preserve Volume* option):

[![enter image description here](https://i.stack.imgur.com/3sHyU.jpg)](https://i.stack.imgur.com/3sHyU.jpg)
The mesh appears to be pinching due to the rotation the arms are using to get into the wave position. Try bending the arms in a more natural way and adjusting weight paint. As of now the shoulder is rolling in such a way that along with the weight paint is causing the mesh to roll too far.