From personal experience ;)
Trying to stretch the tunica while being not even fully erect (80%+) is an impossible task.
I’m probably lucky that it didn’t work hehe. Simply too much resistance.
The only thing that really gets stretched are your ligaments. And some other fully engorged blood vessels which surely appreciate the extra stress ;)
A penile fracture usually is caused by too much pressure in one small spot of your erect penis, say, a hand desperately trying to grip the resisting snake in order to stretch it? ;)
And no, it’s not nice.. Had that “pop” with the first girl I was with (never went to the doctors) and have a slight downward bend ever since..
Ys