I Need Your Help Step-Sis, I Took Too Much Viagra

There are moments when I can be such a fool, I decided to experiment by trying out some of my father's enhancers to figure out the sensation. Currently, I find myself in a challenging situation as I am experiencing an incredibly stiff erection that shows no sign of subsiding regardless of how much self-stimulation I attempt. In a state of panic, relieved that my parents are not present, I urgently approach my step-sister for assistance with my problem.
Requesting Alex's involvement to aid me in reaching orgasm in hopes that it will relieve my condition. Initially met with amusement and rejection, after some persuading, she eventually agrees to engage in sexual intercourse with me until I unintentionally ejaculate inside her.