jaelis
Oh this is where the title goes?
I gave my party this one, that I particularly liked. It was a gynosphinx that was a bit of a prude and warned them to keep their minds out of the gutter (because the answer is clean). This is apparently a genuine riddle from the 10th century (translated to modern English of course). They got it eventually 

Swings by his thigh
A thing most magical!
Below the belt
Beneath the folds
Of his clothes it hangs
A hole in its front end,
Stiff-set and stout
It swivels about.
Leveling the head
Of this hanging tool,
Its wielder hoists his hem
Above his knee;
It is his will to fill
A well-known hole
That it fits fully
When at full length.
He's oft filled it before.
Now he fills it again.