Insulting oneself? More difficult than it seems.

I was having a conversation with my mom the other day, when my sister thinks of something irrelevant and stupid, but which she deems valuable input to our conversation and interrupts. I was speaking about my courses at school, when she begins:

Amy: Hey! Guess what?

Mom: Amy, I'm talking to Cory right now. You just wait, ok?

Amy: No, but I have something you need to know.

Mom: Well, tell me later. I'm busy right now.

Amy: I have a stomach behaviour.

I'm interested enough at this alone that I feel it's worth letting her interrupt so I can hear more about whatever nonsense she's thought up.

Me: What?

Amy: No! I mean I DON'T have a stomach behaviour!

Mom: Ok, that's lovely. Is that all?

Cory: So you decided to interrupt me to say that your stomach feels fine? Was it upset earlier or something?

Amy: No, not my stomach. I have a--I DON'T have a stomach behaviour.

Mom: What are you talking about?

Amy: A stomach behaviour. I don't have one.

Cory: What is a stomach behaviour? I have honestly never heard that term before, and I believe that is because you just made it up.

Amy: No, I learned it in school.

Cory: In what class?

Amy: Sociology (pronounce by her as "SO-so-logy"

Cory: You learned about "stomach behaviours" in Sociology?

Amy: Yeah.

Mom: We have no idea what you're talking about. Describe it.

Amy: Ok....it's when...like, when you do stuff and don't want stuff in return.

Cory: You mean "being nice"?

Amy: Yeah, but it's called a stomach behaviour.

Cory: So where do the stomachs come in?

Amy: There's no stomachs. It has nothing to do with stomachs. That's just what it's called. You know!

Cory: No, I do not know.

My mom and I then spent a few minutes trying to think of terms that sounded like "stomach behaviour" that fit Amy's definition. The whole time, Amy continued to elaborate (very poorly) on her definition.

Cory: So, this "stomach behaviour" means you're nice and do things for others?

Amy: Yeah, like, you do stuff and don't expect anything back.

Cory (after a few prior guesses): I sure hope you're not trying to say "altruistic"...

Amy: Wait, what? That might be it!

Cory: Altruistic behaviour?

Amy: Yeah, altrustic.

Cory: Altruistic.

Amy: Alstrustic.

Cory: Stomach behvaiour.

Amy: Yeah, it sounds better, right?

Cory: No. Hang on, didn't you say you didn't have a stomach behvaiour?

Amy: Yeah.

Cory: So you're saying you're non-altruistic?

Amy: Yeah, why would I want to be nice and help people for no reason?

Cory: ...Let me get this straight...you butted into our conversation to announce that you're a dick?

Amy: Yeah, pretty much.

Then she burst out into raucous laughter and walked away.