Cobb's Curve 

The point where the urethal tube in the male penis begans to curve upward within the human body. It is also the point where several glands are located and the urethra lining becomes more mucous and sensitive. This area of the male urinary system then curves upward into the prostrate and male bladder.

In Urethral Play, the term Cobb's Curve is used to define safe and unsafe sounding and play. For urethral toys located forward of this point (within the penis) are usually easily removed and can be worked back and forth with very little injury to the more delicate parts of the male urinary system. Going past this point, a male must thread straight (solid) sounds through the curve in order to go deeper for play and this presents greater pressure on mentioned organs, not to mention possible injury. Therefore, sounds and toys pass (or going deeper) than Cobb's Curves are considered unsafe.

"My friend Joe lost his plastic urethral toy worm the other day when it slipped past Cobb's Curve and went into his bladder."

Cobb's Curve by Mi Lu Wong June 11, 2007