1. Box Push-Up
To do this variation you will need two sturdy boxes separated a few feet apart. What you do is position yourself in the middle of the two boxes and perform a push up. Then when you reach bottom position explode upwards and land your hands on either box. Now perform another push up this time when you reach bottom position, push off again and land on the ground.
Effectively you are doing 2 push ups per rep here one on the ground and one of the boxes.