At about 09:15 CST, a Piper PA-34-200 had its right main gear collapse on the takeoff portion of a touch and go. The pilot flying the airplane was receiving multi-engine instruction. After touch down, the pilot retracted the flaps and reached for the landing gear instead of the throttles. The CFI yelled no and the student pilot released the handle and added full power. The right main landing gear retracted, the airplane yawed to the right and stopped in the grass.