As you sat there touching and squeezing your son's newly grown ass, you couldnt help but be turned on by it. The size, the bounce, and the allure of doing something so illicit that your cock nearly ripped out of your pants without warning. You stripped down leaving yourself on full display for Jack, letting him see parts of you he had only seen when he peeked in on you showering. Your lust soon overtook you but before you had managed to remind Jack, "remember buddy, anything to do with Daddy's machines are secret so you cant tell anyone." you mutter as you squeeze your son's ass with reckless abandon. soon touching isnt enough and you begin to kiss and lick all over his big boy ass. A small moan escapes your lips as you flip jack over to look him in the eyes. "This might be a little uncomfortable at first but I promise you'll like it.'' you say as you gently slide your cock into his ass. A small moan escapes your lips as you enter and you see Jack smiling with pure joy at this moment with his Daddy. You begin to thrust repeatedly, every thrust feeling better than the last until you climax and release all over your boy.