Bad Parenting Moment

OK, so today I didn't exactly win any parenting awards because I laughed instead of being the stern, serious, reprimanding mother:

Let me set the stage for you: We went to pick up Jason's prescription a the pharmacy. Landyn asked if he could hold it for him. I said yes because it was only nasal spray and I knew he couldn't get hurt with it.
Landyn looks at Kordyn and says: This is my dad's medicine.
Kordyn: NO, it's my dad's medicine
L: NO, it's MY dad's medicine.
K: No, it's MY dad's medicine.
L: Oh, just shut up Bubby! (except is sounded like: on, just sut up, bubby)

And then I laughed before I could get onto him. I just said, Landyn Brock.
Then, Landyn said, "That's what the Germans say." ???Where does he get these things?