What if Truman wanted to "self-pleasure"?
You know, go somewhere he thinks is private, with a porn mag, and proceed to jerk off to it - did they allow that to happen? Did they cut during that time? Or did they forbid him to do it, saying it was "evil" and "against god's will" and other absolute bullcrap?
If it was the latter, then poor man indeed - there's nothing better, aside from actual sex - for having a great time by yourself, naturally.