To protect or overprotect a boy/girlfried in fear that he/she might find interest in someone else. Another way of cuffing is announcing a relationship loudly around a large crowd rather verbally or physically. Think of it as a relationship leash, or handcuffs (thats what it is originated from anyway)
That dude gets any girl he wants in the club. You Better cuff yo girl...
You Dont Let Her Go Nowhere! Are You Gonna Cuff Her Forever?
Although meaning to "make a chick your own", the term cuf can also be used as the word "cuf" with only one F to describe having sex with a girl. Cuff can be used in two different ways.
When used in a sentence where the guy talks offensively about a girl (i.e. bitch or female) the term means "to fuck".
When used in a sentence where the guy talks respectfully about a girl (i.e. girl or chick) the terms means "to date".