Sami says.....
1. When someone gives you something.....you say "Thank you."
2. When you burp.....you say "Excuse me."
3. When you hurt someone.....you say "I'm sorry."
4. When someone is being silly.....you laugh.
So I ask her, what if it isn't funny....she says....."you laugh anyway."
That's what I'd call the "obligatory laugh."