I Forgot the Funniest Part!

I was tired when I finished the Green Eggs & Ham for Dinner post yesterday, and I just kept feeling like I was forgetting part of it.  But I couldn't for the life of me remember.  Until this morning.  So here it is:

First, you need a little background info.  Ethan still has this thing about the "T-H" sound at the beginning of a word.  He says "the", and "they" correctly, but anything else he pronounces with the 'f' sound.  So 'think' comes out 'fink', 'three' comes out 'free', 'thing' comes out 'fing'... you get the idea.  He can say those correctly, but he has to 'fink' about it first, and he just doesn't care.  I've tried.  He resists.  So I've given up for now, and I figure one of his friends will make fun of him, and then he'll start caring enough to say them correctly. Great parenting, right?

Anyhow, we were just done cooking the Grinchy Green Eggs, and he says, "Mom, you know what those remind me of?  They  remind me of the "F" word!
Me:  (Somewhat horrified)  The "F" word?
E: Yes, you know, that "F" word for when you puke.  That "F" word.
Me: (Huh?  What word for puke starts with an F? And then it dawned on me....)  OH!!  You mean, "F-rowing up?" 
E:  Yeah.  That one!
Me:  Honey, that's not an "F" word.  That's one of those "T-H" words that you don't say the right way.  It's throw up, not frow up.
E: Oh, I didn't know.  I thought it was an F word.   The eggs do look kind of like F-row up, though, don't they?
Me: (laughing)  Yes, I guess they do!  (And I still don't know why he called it the F word instead of just saying 'frow up' to begin with.)