If your dad is cool and he says it, he's pulling you aside to have a confidential "coaching" moment, while saving you the embarrasment of having your friends hear the whole subject.

Can also be said to someone about your own age who is being a bit naive, for example about a girl who might be bad news, but who your homey is starting to get caught up in. You might say to him "can i speak to you son" as a way of letting him subtly know he might want to talk to you because there might be something you know that he might want or need to know.

A pubic hair piece. A toupee for the pubic area/genitals. In the 1700’s when mercury was used to treat sexually transmitted diseases (Gonorrhea or Syphilis) one of the side effects was the loss of pubic hair. To disguise this condition, that was not cured by mercury, a Merkin was employed.

If said by dad, you are FUCKED. That is, unless you play the "SHUT THE FUCK UP BEFORE I POP MY GAT AND SHOOT YOU IN THE FUCKIN FACE!" card.