Since all Air Force basic training and the majority of ROTC officer field training takes place at Lackland AFB, in sunny San Antonio, almost everyone in the Air Force spends a significant amount of time doing push-ups in Texas. If you spend long enough in this position, especially in the summer, it may seem that you're upright, and you're "pushing Texas" away from you. A drill sergeant (or military training instructor, or field training officer) will often tell you to do push-ups by simply ordering you to "Start pushing Texas." During your push-ups, he can then call the dubious encouragement, "I don't feel Texas moving--PUSH HARDER!"
Because some training takes place in other states, you may hear someone occasionally talk about "pushing Georgia" or "pushing Alabama", etc. These are probably all the same, with the distinction that everyone you meet will tell you that his training was the hardest. Don't believe them. Mine was harder.