2 years pass. The time comes for you to take your exams to see if you have accurately learned the language. Reading and writing have begun, by now, and you are to be tested on them as well. You do take the exam, and are astounded to find that you are FAILING! Why is this? Because you have been allowed & encouraged to learn incorrectly every single one of those "funny" or "cute"-sounding phrases, imagining them to be correct.
I am seeing this unfortunate practice take place before my eyes. A mother chuckles at her child's mispronunciation of the word, "with." Then one day in First Grade, she sees a big red "F" on his spelling test. She looks down the page at the words he sounded out. She reads, among others, the word, "WIF." This child has great learning skills, he's a perfectly normal child, he has just repeatedly been given the wrong information. He thinks, because his mother laughed at the cuteness of "wif" that it is correct. When asked to spell it, he spells it the way he's been saying it for 5 years. W.I.F.
This, people, is why it's so so important to remember we're raising Future Adults here. From the moment they're born, children are preparing to become adults. If we keep this in mind and don't hinder their growing up by teasing, cajoling, mocking, laughing, and all-round promoting permanent babyhood, they'll be so much more secure as adults. Babyhood is cute when it's exhibited in a 2-year old, but when the same things are present in a 9-year old, we call it misbehavior and it's shameful! Or, in the case of the Public Education System, we call it "failing First Grade."
Let your kids be cute, but remember they need to be given the dignity of being trained as next generations' adults. And, yes, they have to pass First Grade, as well.