Family Ties/Tell Jacob to stand up so his mother and sister can take a look at his cock.
You give Jacob a look. That look. You've had enough teasing and taunting.
"Come out here Jacob. Stand up."
Jacob's look of intrigue washes away from his face, replaced by a horny nervousness. He starts fiddling under the table again.
"No no no," you scold him. "None of that. Just get out from behind the table. Show your sister and I what you've been doing."
Jacob rests his hands carefully on the table. The small seating area doesn't give a lot of room to move around in. He is forced to slide his way along the seat before he can stand beside the table and next to Jess.
"Mmmm... hello there," you coo to your son's cock.
His boxers have slipped down to his knees. His shorts are at his ankles. A small tuft of pubic hair rests just above the base of his cock, the form fitting wife beater you picked out offering little coverage below his belly button. Jacob's cock stands at nearly six inches, an admirable size for your newly teenage boy, and it is indeed standing. He is stiff as can be, the uncut prick bobbing in the air desperately straining to grow even larger.
You notice Jessie staring down in awe at her brother. You've had your suspicions that the twins may have "experimented" in the past but from her expression you're certain this is the first time seeing her older brother's manhood. It's your first time as well, but your expression is a bit more lustful.