Limericks (technically speaking)
The limerick competitions we run every month in mini-AIR somow always draw (in addition to some good and some bad limericks) a large number of entries that — technically — are not limericks. For good examples of limericks that are limericks, see the OEDILF. For concise pointers on writing limericks, see Peter Macinnis’s how-to essay.
(Thanks to Glenn Glazer for bringing this to our attention.)