"Wabbits" joke

A little girl walks into a pet shop and asks in the sweetest little lisp:

"Excuthe me, mithter, do you keep wittle wabbits?"

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 black wabby or maybe one like that cute wittle brown 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 weally gives a thit."