well first off, thanks for the proper spelling of boobie. Secondly, His mom shouldn't feel the inclination to ground him just because his sister "broke" into his room while she was feeling snoopy, and rummaged about in his personal belongings. It's not his fault that she happend to mess with his stuff that also just happend to be in the same location as his mouse traps. If she had a little more respect for other people's things this whole problem would have been avoided. Lastly, mouse traps won't break your fingers (at least not the small ones. Larger rat traps may). I know this because when i was four a reached into a closet and set a mouse trap off on my hand.
Anyway, I didn't think he was going to do it, (just trying to be funny) but if he did, more power to him.