Inguinal hernias are weaknesses in the abdominal wall, where segments of the intestine can enter and get stuck, or incarcerated. That incarcerated hernia occasionally can get blocked or twisted, depriving it of blood, requiring emergency surgery.
The nuts are checked for masses, testicular cancer being one of the things to watch for.
The digital rectal exam means a finger up the breech, the examiner looking for abnormalities in the prostate (although that is more of a concern in older men).
Physical exams are a chore, and doctors tend to remember you only if they find something wrong. So if you meet the medical officer again he might not even recognize you.