Each September, a hoax mocking 18-year-olds’ excessive masturbation circulates on the internet. But what does the science say? Susan Monyak looks into it for Slate. When the reporter could not get interviews with maintenance staff at the universities, she turned to the scientific literature. "As it turns out, there appears to be very little research published on the direct effects of semen in shower drains (free thesis idea)." Ultimately? The conclusion is that semen doesn't clog drains because even though it has a sticky gel-like consistency at first, within half an hour it becomes a runny substance, much like water.