If you didn't believe that sex is fun, well, here's the proof. ha. Sure, some porn, sex toys, erotica, stories, or less dry personal experiences could have told you that. but in case you're a hard case, here's the hard-line case that a hard-on can lead to a good case. Now while this proof is admittedly a bit less enjoyable than the rest, it's exponentially less embarrassing if your parents walk in on your, uh, studies.