...shed his tongue against Bart's tender anus.
"Ohhh, good boy." Bart praised, turning and laying on the floor. "Now lick my pee-pee." The dog brought his muzzle to his master and again curled his pink tongue against Bart's yellow head. He felt his shaft contract, and a glob of precum oozed out, only to be swept up by his pup's rough tongue, a strand of the sticky fluid stringing from his slit to the dog's lips.
Santa's Little Helper stopped abruptly, and backed off. He sat down and curled his head back to his own crotch. Bart could see his pet's own bright pink penis extending from its protective sheath. Curious, and suddenly feeling guilty at the one-sidedness of the exchange, Bart crawled over to the dog.
"Good boy." Bart told him as he stroked his fur lower and lower down his side, until his hand curled around his pet's foreskin. He softly massaged the dog's balls and stroked his sheath. Slowly, the tubelike tip of its head crept out. Santa's Little Helper jerked when Bart gently touched it, but deciding that his master meant no harm, let him pet it for several seconds.
Looking down at his own genitals, Bart could see a huge amount of his own clear fluid trickling down...