Silicone Masks are Designed to Have a Memory Fit

New divers frequently share scuba masks, use loaners or rent their equipment. Invest in a new dive mask, if you want it to fit properly and function well.
The easiest way to spoil a dive is to wear a mask that does not seal to your face. You will constantly be clearing water from your mask, or heading to the surface with irritated eyes.
The pliable skirting on quality masks is designed to mold to the contours of a diver's face. The soft silicone material will hold that shape -- unless other divers try to use the same mask.
If you borrow a friend's mask, the mask likely will leak because the skirt won't fit your face. You also will destroy the "memory" fit for your friend.