A Joke

Sam is really into telling jokes.  Most are knock-knock, but she only remembers one, so it's the same one over and over and over, then tells me it's my turn.  After it's my turn, she then tells me the same joke that I just told her.  It's cute, but I usually make it through five rounds before I'm done.
To spice things up, I taught her this one:

My mom didn't get it, so she clarified, "Get it mimi?  Seven EATED nine!"