Premature ejaculator humiliation

You only come to realize later on that coming to your step sister's room to ask for relationship advice qas a big, biiiig mistake. But it's already too late now, since she already knows that you are a premature ejaculator and is planning to tease you about it for the rest of your life. But since you wanted to know what you could do to last longer, she comes up with the idea of a challenge, where you try as hard as you possibly can to last for the number of minutes she chooses. Of course she will tease you while you jerk off and gradually increase the number of minutes you're supposed to last for. It won't be easy but maybe you'll make it...never know :) will you?