LOL!! My four-year-old very rarely repeats things I'd rather he not say. But you're right: It's hard to not crack up laughing at the way they say it sometimes.
You oughta hear him repeat lines from Mystery Science Theater 3000 shows. Too funny!
HA! When my nephew, who is my older son's age was about 3 yrs. old (now this kid is damn near genius type smart and has a really high voice and a lisp when he gets angry, right?) was having a bit of a tantrum at my mother's house and my sister-in-law was FED UP? She's trying to get them ready to leave, but you know, there at grammy's house, right? They don't want to go.... So after putting up with this little tantrum for about a good three minutes, she leans down in a wagging her finger at him stance and says "ETHAN, YOU RESPECT YOUR MOTHER!!!" Without missing a beat, he looks at her dead in the eyes and says "MUMMY, YOU WEETHPECT YOUR THUN!!!!
Randall, you had about six adults, including my sister-in-law turning toward the wall busting a gut laughing and trying not to show it... HYSTERICAL!!! : )