Stem flats! I hate 'em. Mostly I cause 'em. Now, I love my HPX full size frame pump and won't part with it. I've used it to threaten dogs, made people laugh by using it to simulate farts (the boyish side of middle aged guys riding together), have "almost" stuck it in the spokes of OCP's or anyone faster than me, etc.
But, I have also used it so vigorously, carelessly, and without securing the wheel against something because I'm lazy and in a hurry.......that not infrequently my 5)#@+ pumping causes partial separation of stem from tube----pppssssstttt! Try patching that one.
Betcha nobody else here does that.