haha I did that warming up with like 135 on the bar hit myself right in the chin and I almost knocked myself out. I had to rest about 10mins before even attempting to continue.
On a side note, my new school gym has trainers from 4-5PM. I was warming up dead lifting 225lbs not really caring too much about farm just trying to get my blood flowing and this guy comes over and gives me a lecture about how it was a lot of weight and wanted to make sure I had good form. He wouldn't leave me alone I think he thought since no one has done over 3 plates (I goto a pussy ivy league college) that I might hurt myself.
Two days later I am doing squats and some kid asks to join in. I'm warming up and he was saying that I went too deep in my squat (olympic style), and his 1/20th ROM were a lot better. I still out squatted him which was great.