babies in a crib

there are two babies in the same crib. the first baby says are u a boy or a girl.
Idk said the second baby
the first baby crawls over to the second and goes underneath the blankets. a few moments later the first baby comes out with a big smile on his face.
he says ur a girl and I'm a boy.  ur so clever   how do u know  well its easy says the first baby  I have blue socks and u have pink socks.