How does water based lotion get absorbed into your skin when your skin is waterproof?

Dexter Dicostanzo: skin also absorbs moisture

Marcellus Yoshimori: Skin isn't waterproof

Efren Clankscales: my anatomy & physiology teacher said skin is waterproof and asked the class, how then can water-based lotions get absorbed into skin. if anyone knows how this process works it would be very helpful. Thanks