i ill tell you a nasty true story about why not to wear these

a colleague i trained with in mid 80's got caught by a low blow. Unfortunately his gonads has slipped out therefore he got caught etween the edge of the cup and his leg, the result........

one split testicle

i normally take the cup out and wear it under a very tight pair of speedos so the thing has not movement capaility at all
streakers - your end is in sight