Wittle Wabbit

A little girl walks into a pet shop and asks in the sweetest little lisp: "Excuthe me, mithter, do you keep wittle wabbits?" And the shopkeeper gets down on his knees, so that he's on her level, and asks: "Do you want a wittle white wabby or a soft and fuwwy bwack wabby or maybe one like that cute wittle bwown wabby over there?" The little girl puts her hands on her knees, leans forward and says in a quiet voice: "I don't fink my pyfon really giveths a thit."

Pardon Me

Q: What's long and green and goes "hith"?
A: A snake with a lisp.

Knock Knock - Cow

Knock knock.
Who's there?
Cow goes.
Cow goes who?
No, cow goes "Moo!"