Some guy was humping the big ball the other day right in front of the damn dumbbell rack.
He was trying some hybrid between a one hand push up and abdominal crunch.
Stupidest shit I seen in awhile.
if it's fun for them to get a good balance feel for themselves without building muscles that's their thing, no reason to critic them.
obviously they know the injury risks and are glad to take them,
same with people lifting heavy weights for many reps take the damage to their tendons and ligaments, they could make fun of you, too.