I present what I would like to call, the Ultimate Shower Beverage Holder. I've designed two models, one to accept a large suction cup, and another to work with a 3M strip or other form of adhesive.

This will hold standard sized cans and bottles. I've also designed the top with enough space to hold a portable blender, in case you want to enjoy your post workout shake. I've also added a spot to place your phone, if you want to listen to some music or watch something on TV.