Drop Out is a combination of Squirrel Crossing and Hot Pepper. The goal is to improve volley skills, good hands, recovery, and reaction time. Players should be able to volley so advanced beginners and up. Five players or more is best. If you only have 3 or 4, restrict play to one half of court either straight ahead or diagonally.
Four players begin facing each other across the net. First ball is fed. Point is played out. Ball must not hit the ground. When point ends, whomever has made the error is out and a new player comes in.
From The Tennis Drill Book by Tina Hoskins.