I had some pretty bad turkey neck. Mine was the result of being circumcised too tightly and the skin needed to accomodate my erections was "borrowed" from the scrotum. The problem with skin expansion is that a certain amount of stretching force has to be applied to the skin regularly to cause the skin to permanently lengthen. When we are circed too tight, or gain length from Penis Enlargement, the skin of the shaft doesn't grow to accomodate because the hair bearing skin of the pubic area and the scrotum merely slide up the shaft a little and there is no stretch. The result is a hairy shaft with an ugly flap of nutsack hanging from the bottom side.
Although binding the testicles and BE do work, I'm sure, I have had more success fixing my turkey neck problems with a simple erect skin stretch.
Just get yourself nice and hard and grip the shaft loosely about midways, then pull down firmly toward the base of the penis, holding for twenty seconds or so, and repeat for several minutes. It's not going to feel good because you are stretching the inner mucosal tissue of the penis (the lighter colored skin above the circ scar) which is more sensitive. In fact, it's probably going to hurt a little. The plus side is, you are going to expand that more sensitive tissue and end up with a larger area of sexually sensitive skin while at the same time ridding yourself of turkey neck.
If you are uncircumcised, you are going to have to try doing this two handed. While holding the skin firmly with one hand near the top, stretch downwards with the other in a kind of tug-of-war type stretch toward the base.
When you are done, apply some vitamin e oil or lotion or something to sooth your skin.
I noticed results within a couple weeks of doing this exercise. It didn't cure the turkey neck instantly, but did make it noticeably recede.