The genre blender Xtro. Best summed up by this review:
"Bizarre alien horror movie about an abductee who returns three years later in alien form in order to abduct his son. He goes through several transformations, one of them by impregnating a woman through her mouth and gorily emerging a short while later as a full grown male. He transforms his son by sucking on his shoulder, who then joins him in bizarre activities like melting phones, creating a killer midget clown and stuffing the babysitter into a cocoon so that she can lay eggs. No, this movie does not make any sense."