Hay(na)ku is a 3-line poem of six words with one word in the first line, two words in the second, and three in the third. There are no other rules and no restrictions on number of syllables or rhyme.
As you'll see from the examples, some folks create poems comprised of several hay(na)ku strung together. So, what kind of hay(na)ku will you write? Leave me a note about your poem and I'll post the results here later this week.