Simplest tech ever. When you are in the pushup postion bring 1 knee up and then down. Then do that with the other leg. Shitty explanation but its really simple. Some people do it just as an excersize.
what is you were doing a jackhammer and bicycle pumps at the same time, that would be pretty sick imo. Well... in theory it sounds like it would look dope, but if done wrong it could look horrid.