I'm going to shred all my girlfriends letters from Peta
Why would you shred her letters from PETA?
I hate that Peta shit from her.
Peta is an organization that your seem to disagree with on all accounts. Have you tried to learn what Peta is really about? Shredding other's mail without their permission is considered tampering with the mail and you can be prosecuted for that.
I think Peta is killing animals for no reason and I'm going to do everything I can to destroy this shit.
Why would you assume PETA is killing animals? You need to do more research about them. And regardless, you should never destroy someone else's mail, that's against the law.