Nobody has submitted a 'true' limerick yet.
"A limerick has five lines, with three metrical feet in the first, second, and fifth lines and two metrical feet in the third and fourth lines."
Example:
The limerick packs laughs anatomical 
In space that is quite economical, 
But the good ones I've seen 
So seldom are clean, 
And the clean ones so seldom are comical.