I thought it'd be an evil little file. It'd maybe have subliminals arousing you while increasing the stimulation required to orgasm. So you'd be a stud by lasting longer, but it'll take longer and longer to orgasm each time.
I thought it could be mixed with penis growth too. So it basically makes you a sex toy. Your partner will cum first and maybe even multiple times but you might not even get to cum before your partner is worn out. If you do orgasm it will be incredible though. Keyword being IF. Your balls will grow too, to make sure your orgasm comes with a matching huge load.