Testicle out ball sack?

When I used masturbate with my legs wide apart my balls seem to slip out my sack but would soon pop back into place. Now I masturbate with my legs narrow together to avoid this. I really want to masturbate the older way again but I was wandering if this is dangerous to my body, like is there a chance I will loss my balls of they slip out the sack or will they always pop back into place?