reach up behind that bummper and push it out by hand.
I was driving my gfs car a few weeks back and was not paying attention backing up (getting tired of driving) and wanged someones car.
When they came out i told them I had experience at a body shop and popped the bumper out. no insurance claim and only a few creases in the bumper, not more than their deductible though.
Car need to have better bumpers if they can't put up with more than a 2-3 mph fender bender, it's should bend back too.