How to tell if a guy is hand-cuffing
1.) The girl he is with is much too attractive for him
2.) He has a worried look on his face and keeps scanning the bar/club/mall for potential threats.
3.) They never touch or kiss, he just kind of looms in her personal bubble, hoping for more attention.
If you see a guy hand-cuffing, go talk to his girl. He won't say anything; he will just stand there quietly with a slightly sour expression on his face until you are done.
Joe: Nah bro, she's with her boyfriend. Don't you see that guy hanging all over her?
Jim: Man, he's just hand-cuffing... See how scared he looks? He has a fauxhawk, and she probably dressed him. She needs some testosterone in her life, I'm going in.