Oh, the young (and those with a small, um, vocabulary), they think what's new to them must be new to the world.  The term goes back a long, long way and has always been a derisive term for men whose women stray.  I think it's from the Old English or French for cuckoo, a bird that apparently lays its eggs in other birds' nests.  Never been a word a man wants to hear from another man, it's been an insult for centuries and I'm sure has its equivalents in many other languages and societies too.