It's a turn-off for sure. There's no need for it to be the size of a forearm. Sometimes it can be funny, but most of the time it looks like it's gonna tear through the abdomen.
Unrealistic body proportions are still okay, fantasy is interesting, but when someone goes overboard and the breasts are three times the size of the head, the ass five times, and the dick could go through two women from bottom to top at the same time, then it's more like some kind of mental distortion