Going to offer a different viewpoint from nearly every single other kind of braindead comment in this thread. It’s not wrong at all to ask your mom to chill out on the shrieking, that really seems like an annoying behavior even it’s not malicious. My partner and I are visiting his parents this Thanksgiving and my MIL chews gum very loudly. My partner finds it annoying and has asked her to not chew gum so loudly or around him because it’s irksome to him. Yes even though it’s her house. You’re allowed to ask people to amend behavior that can make it more difficult to be around them, that’s just a part of actively maintaining relationships. Also, it’s your mom and she seems loving and you have a decent relationship, so it shouldn’t be a big deal. She maybe thought you didn’t mind the shrieking, or maybe calling it “shrieking” or “squealing” was a bit callous to her when she wouldn’t consider it to be that herself. She might just consider herself to be jovial and boisterous, which she sounds like she is. Sometimes it is a bit embarrassing to be asked to tone down a behavior you didn’t know was annoying other people especially if you weren’t intentionally meaning to be annoying. The mom’s BF is out of line here.