My favorite piece of man trivia is from the source of the tunefs BSD man page, which contains:
.\" Take this out and a Unix Daemon will dog your steps from now until
.\" the time_t's wrap around.
.Pp
You can tune a file system, but you cannot tune a fish.
There was also the record You Can Tune a Piano, but You Can't Tuna Fish by REO Speedwagon, I had assumed that's what the tunefs man page was referencing as that was a best-selling record at around the time Unix was being developed.
