A language quagmire

As I was knotting strings so C could do a lacing pattern:

Mommy: "There! Go knot happy!"

C: "Are you unhappy mommy?"

Mommy: "No, I'm rather chipper today. Why?"

C: "Well, you said 'Go not happy' and that doesn't make any sense."

Mommy: "Oh, I meant knot as in tying knots, not not as in no..."

C: "Huh?"

Mommy: "Knot as is k-n-o-t not n-o-t...oh, damn the English language."

C: "Mommy, Mrs. K says damn isn't a nice word."

Mommy: "Grrr."

C: "I'm still a little confused about the k-n-o-t thing..."

Mommy: "Double grrr."