What are specific symptoms of appendicitis in a guy?

None are specific: You can have belly pain (or not), vomiting (or not), loss of appetite (or not), and other symptoms (or not). The best thing to do is see your doctor to be checked out and find out what is going on. Don't try to diagnose yourself.

RLQ pain, anorexia: Classic appendicitis symptoms are: pain that starts near the belly button and is crampy, and then moves to the right lower abdomen and becomes constant; and anorexia (not being hungry). Fever is common, and many have nausea. Most don't have vomiting or change in bowel habits. Symptoms can be atypical if the appendix is located somewhere other than the normal place (in the right lower abdomen).