The more porn you watch, the more hardcore the porn has to be for you to get an erection and to finish. For example, if you watch porn sporadically regular straight porn will do the trick. However, if you're a Giesel and masturbate 13+ times a day it will take some seriously hardcore bukkake or brazilian fart porn to get you off.
Palmer: Dude, last night Lesnick was locked in his room for like twelve hours straight masturbating. You know he had to be wanking to 2 girls 1 cup or some beastiality incest or something.
Pat Shea: How do you know that?
Palmer: Cuz of Giesel's Law of Diminishing returns, that's how