When ones nad
(s) become a bit red (usually through excessive itching/scratching) and commonly causes the sufferer to have to give them a good scratch with the intention of relieving the irritability.
However, this can have a snowball effect as scratching causes more redness, causing more irritability, causing more scratching.
Excessive scratching/attempts to relieve the annoyance (and ocassional pain) can cause the sensitive skin around the area to crack.
Many - STI, regrowing pubic hair, ants in yer pants, coarse pubic hair, uncomfortable underwear, woolly underwear, another person playing with your genitals (hopefully a girl).
Course of action:
Brief, gentle scratching of the area can relieve symptoms.
However persistent nad rash may need one to seek medical advice.
N.B. there is a female equivalent but most females are either too polite and "lady-like" to let everyone know about it, or relieve themselves with a good scratch. Females will generally wait until they are alone, in the company of those who they are comfortable with, grin and bare the irritability until such a point when eveyone has left, or make an excuse and proceed rapidly and uncomfortably to the nearest restroom
(a common female nad rash gait has been noticed by scientists and can be subtly picked up by those with a sensitive eye)