A "turtle" (ie TURD-le) is what you call someone who is a little turd (or little
shit). It is used when you don't want them to know that that's what you actually think of them.
Turtles are usually young males who think they're better than everyone else, they often call themselves "alpha males" but they're actually not, they're little shits or turtles.
Often the fathers of turtles
will excuse the
poor behaviour of their sons by proudly saying "Oh don't mind him, he's just an Alpha
male."