Do I tell my parents what my sister and her friends did?

[Anabelle]

If I were you, I would definitely tell your mom.
Once when my little sister (12) was listening in on my phone calls, and then she looked through the tiny hole that is between our rooms in the corner and her and her little friend (a guy) saw me in my bra and underwear. My mom grounded her for 1 month, no phone, internet, or friends. Then when she wasn't grounded anymore, my mom, dad, and I went in her room whenever she was on the phone, put it on speaker and listen to the whole conversation until she learned that what she did was wrong. We also sat and watched what she was doing on Facebook, Myspace.... Thats what I would do, if I was your mom.

<3Anabelle