I thought the same thing before using it the first time. But, it holds perfectly snug inside that jock. I guess it's the shape of the cup. I hope I never need this baby's protection, but I'm 100% comfortable that it won't dislodge before it's needed.
Never had a cup shot? For me it seems to come sporadically at times. Last year I had four shots to the cup in two weeks! I ate good that week from all the bag of peas I thawed out! I washed the peas good before cooking btw!