My pumps have an adjustable collar to let me loosen the fit on the stem without being overly snug, but they're not the coolest pumps in the world, just basic.
I was headed out for a ride with my kids last month and adding some air in the garage, pulled the pump off and put it away, but before I got back to the bike the valve shot out of the stem with a lot of fanfare. I was well startled and my kids thought it was cool (of course). The bright side: the driveway / yard has got to the best place to teach / learn how to change a tire!