Yes you should. A hard cup should be worn during Baseball to prevent injury.
Wear a jock strap.
Put the cup in the jock strap and tell him to wear it like underwear...
Not usually. Usually when you have a jock on, you don't wear anything else with it, just your athletic gear on top of it. However, if you are wearing compression shorts, sliding shorts, hockey shorts, etc., you should wear those over the jock. Some people (inexplicably) wear a jock under a swimsuit, too. If you're wearing the jock for running or track, you just wear your normal shorts over the jock, no underwear. You can wear a lot of modern underwear (briefs, gripper jams, etc.) INSTEAD of a jock, particularly if the underwear fits closely and is supportive.
the one you can wear in public
a lot of modern football players wear compression shorts instead of a jock. Compression shorts do not hold the penis and testicles as firmly as a jock does.
wear a jock with a hard cup, or wear tight speedo under the singlet.
Yes, in fact, it is a good idea to wear one when you work out or play sports.
Jock Somerlott died April 21, 1965, in Butler, IN, USA.
Jock Somerlott was born October 26, 1882, in Flint, IN, USA.