First broken item in chem lab... and it was my doing.
Knocked a 400mL beaker off a counter, empty, clean, no problem. Clipped it with my hand, knew it was going, but all I managed to do was get my foot partially under it, not enough to keep it off the floor.
TA had the usual questions, anything in the beaker, was I injured, et cetera. No real problem. Lined jeans and 8" tactical boots, I'm pretty safe.