A limerick is a rhyming poem or a humorous song.
Michael Sullivan, while discussed the topic of poetry with Kathryn Janeway, noted how much Jane Eldon and Sean Gogarty shared similar rhyming schemes. Janeway was, however, not familiar with either poet, and was told by Sullivan that she had some catching up to do, and invited her to join him sometime. Sullivan further explained the one time he tried talking poetry with Seamus, but that "all he can do is recite limericks." (VOY: "Fair Haven")
Harry Kim considered tweaking Tuvok's holo-program of the Temple of T'Panit, so that instead of Vulcan prayers, the monks recite Ferengi limericks, in attempt to make Tuvok laugh. (VOY: "Ashes to Ashes")