they are talking about APDDTTF, a serious medical condition caused by the use of AAS.
here is an excerpt from a medical website
APDDTTF (Advanced Penile Deformation Due to Traumatic Testicular Failure)
APDDTTF is a condition in which the male penis "falls off" due to a severe disruption in the patient's HPTA (Hypothalamic Pituitary Testicular Axis). Prior to the penis "falling off", the patient's testicles recess in size to the point where they "dissapear". The glands remain intact, but the volume is reduced so greatly that the testicles can not be detected. At this point in time, the patient's HPTA is disrupted so greatly that severe depression, anxiety, and lack of sex drive are prominent side effects. If the condition is not treated in it's earliest condition, the penis will undergo a transformation. An erection will become impossible to obtain. Blood will eventually cease flowing to the penis, in which case it will wither and fall off.
this is why PCT is so important.