Hang up the guns

To Retire, settle down.
It's based on the idea of an old gun slinger who finds true love and 'hangs up his guns' to become a farmer.

In modern usage, it could be said about a guy who has previously had lots of casual relationships, or considers himself a 'playa'

"I tell ya man this chick is sooo sweet!"
"So you gonna hang up the guns?"
"Holstering my weapon as we speak"
"Mug!"

by Lazy Diamond June 19, 2009