On Linux (if you have Fortune, which comes with bsdgames), do this:
fortune -a -m "There once was a man from"
To quote the manpage for -o (offensive, which is included in -a):
Please, please, please request a potentially offensive fortune if and only if you believe, deep down in your heart, that you are willing to be offended. (And that if you are, you'll just quit using -o rather than give us grief about it, okay?)
Here's one:
There once was a man from Sydney
Who could put it up to her kidney.
But the man from Quebec
Put it up to her neck;
He had a big one, now didn't he?