Garage and a limo

A boy goes into the toilet with his mum and goes "mum what’s that" and she replies "it’s a garage". So the next day the boy goes in with his dad and says "dad what’s that" and his dad replies "it’s a lime". Then the boy asks daddy "what have I got" and his dad replies "lights". So that night the boy is in bed and he gets scared. He goes into his dad’s room and his dad says "what ever you do son, don’t lift up the covers". But the son lifts up the covers and he says "daddy why is your limo in mummy’s garage" and then he says "can I come in too?"