IMPORTANT: This trick is awesome but is recommended for only people with netted trampolines. If you hurt by this trick in any way it is because you have failed.
Needs: Two people at least.
Trampoline with netting
Step 1. Start jumping with the other person.
Step 2. When you feel it's right fall on your back, (usually it's when the other person is going to be as high as possible).
Step 3. When you land on your back force your body to fly back up.
Step 4. Tuck your knees in air.
Step 5. If done right you should have done a weird flip thingy.