When one is minding one's genitals pleasurably (i.e. masturbating) while using pornographic material, and one wants to "complete" (i.e. jizz) but it is in the back of the mind of that person that he/she could always find a better video to complete on. This continues in an ongoing cycle until your genitals finally give up and end up being temporarily or permanently scarred depending on the person.
Dammit, man I won't be able to masturbate for a month! This is the last time I'll fall for the jerktrap.