Yes, you risk it.

You hesitate. Your sister licks her lips and says in a sensual voice: “Do it, its a good one!”

You cant resist. You want to see..and feel what she will do today. And you want to prove your progress. Show her your endurance, your stamina that you gained after suffering in the belt for another 5 days. You take your dick out, semi-hard at the moment.

Sister: “Last time we got you used to the feeling of vaginal fluid. But it was still my hand that you felt on your dick. A girls pussy is very different. Its the inside of a female body. Its much more similar to the feeling of the inside of a mouth. You must get used to that feeling.”

Does that mean what you think it means? Will she…really?…. Your sister grins, and takes your dick in her soft, dry hand. She slowly moves her head down towards your dick, while looking into your eyes. She then opens her mouth, and very slowly, gives your dick a little lick. Your heart skips a beat. Is this really happening. She then gives one long slow lick from the base to the tip and says: “Are you ready? Remember, 8 minutes at least.”

You: “I-I dont think…that…i can manage that long..”

SIster: “Think about what we trained, visualize it. If you cum early now its gonna be so embarrassing, and so bad, dont cum just dont cum! Keep on saying that to yourself, while thinking about the beginning of sex, with..”

That moment she took your dick into her mouth completely. While moaning slightly, she moves up and down, this warmth, this wetness…Your sisters tongue on your dick, her thick perfect lips around your shaft, her head in your crotch… You feel the orgasm cumming…you cant stop it…You moan…and you cum, hard into your sister mouth.

She comes up, spits your cum onto your face and starts to laugh wildly: “HAHAHAHA, that was 1 minute, what pathetic minute!”

You are still shaking, and little drops of cum still drip out of your cock, while your sister laughs at you without inhibition. This is so humiliating…

After calming down, her smile turns into a look of sympathy. She bends down, and gives you a sensual kiss on your lips. That moment you hear the familiar click sound, and she whispers: “7 days.”

You know you are fucked.