Little Johnny is busting for a pee and runs into the bathroom...

Little Johnny is busting for a pee and runs into the bathroom where grandma is in the shower.
He looks between her legs and asks "what's that".
Grandma says "it a beaver".
Next day little Johnny is bursting to pee and he runs into the shower where his mother was taking a shower.
He goes up to her and points to between her legs says "that's your beaver".
Shocked the mother says "yes that's right but how did you know that?"
Little Johnny said "grandma told me but i think hers is dead with its tongue sticking out."