Just don't get hit and spar more. The random punches received in sparring is enough to toughen the body. Worry about not getting hit. And don't let them hit you in the liver because that's crazy and you'll end up in the hospital.
My God. Just extend your arms to the ceiling and ask someone to give you left and right body hooks, slowly increasing the intensity. Breathe out on each hit. When you can't take it no more, the signal: Drop your hands. Now repeat that with a frontal body shot to the abdomen / solar plexus area.... Hypnotiq. You can't expect to absorb all this in such a short time. Dude....
You can do whatever you want. Getting punched in the stomach toughens up your muscles and prepares you for getting hit. He's asking a good question.
some tough skinhead mexican guy always used to do that to the new kids over at the AM gym. he'd take a break in the middle of the spar, and just let them wail at his ribs then counter after about 15 seconds tellin them they best bring their hands back to their chins :nono