When I was in my late 20s, I visited a urologist to have an STD exam (spoiler alert: it was negative). Part of the exam included a screen for genital warts (HPV) that required the doctor to apply acetic acid (essentially, vinegar) to the skin and head of my cock and to exam every square milimeter of the skin, shaft, and head close-up using a mono-magnifying lense. With a female nurse present (I had already changed from my...