"Bamnit"

On the way home from picking LG up from school today, MJ asked if she was going to a birthday party (LG is going to one on Friday).  I told MJ no, and she responded with, "bamnit (that's damnit to the layperson), of course I'm not"!  I asked MJ what she said & she replied, "bamnit".  Yes, I laughed.  LG said, "mama, I think she really said damnit?  Isn't that a bad word?  Why are you laughing, mama"?