Is pushing back your cuticles bad for you?

My friend wants to be a nail designer when she is older, so i asked her if she could try something on my nails. She takes a pair of tweezers and starts pushing back my cuticles all the way until they get bunched up to the point that you cannot see them at all. I say to her "Isn't that bad?" and she replies, "No, i chew and bite my cuticles clear off all the time and nothing happens!". For some reason i don't think i can trust her with that answer, are pushing your cuticles back and/or biting them off bad, or is it just like dead skin?