locksmithing

When a woman is too tight for penetration so you persue the vagina with your hands first in order to "free the lock"

Larry's dinger was having trouble getting inside his girlfriends vagina so he used his kills in the ancient form of locksmithing to pave the way.

"Hey bro, Cathy was so tight last night... I was nervous that is wasnt gonna happen"
"What did you do?"
"We'll luckily i knew a primative amount of locksmithing"
"Genius bro"