Double-dactyls are a form invented by Anthony Hecht and Paul Pascal. Wikipedia has a definition and some examples here, with links (via the Wayback Machine) to the pages once linked to from this page. Here is a self-referental example from me:
Anthony Hecht said a
name in the second line’s
par for the course.
Rhyme in the last lines (each
only four syllables)
end the discourse.
At my original website I issued a standing invitation to send me double dactyls for display at the site, and most of them have moved here with me—links on the left, by author—and I’m renewing that invitation here. I wasn’t picky about strict adherence to the form then, but I’m getting pretty crotchety in my old age, so I’ve dropped a few from the old site and I’ll accept only good-faith attempts here. “Good-faith” means what I say it does on the day I make the decision. You retain all rights. I won’t censor content except as the law may require, meaning if I get a business letter from a lawyer I’m not spending my time and money to keep your poem here.
So send them if you got them in the body of a plain-text email. I’ll reply ASAP.