Ok, here's what I wanted to say but now finally have the time to type:
There are essentially two reasons to write haiku (traditionally)
1) instead of a photograph, you write a brief verse about an occassion or a place you visited.
2) there are also "haiku parties." there's a specific name for this, but I don't have my notes here and I can't remember, but this is how they work:
It's an improvisational poetry session, and you may work with as many threads as you have people writing together. Each thread goes like this:
The first person writes the traditional 5-7-5 section.
The next person writes a couplet of 7-7.
You alternate on each thread. So it's best to have an odd number of threads because otherwise each person is always writing either 7-7 couplets or 5-7-5 sections.
Each section refers to the previous section, and ONLY a the immediately previous section.
So the first two people will have collaboratively written a verse of 5-7-5-7-7. But then the second and third person will have made a verse of 7-7-5-7-5, and the 7-7 will from the first and second will be the same.
Many haiku you find in collections are made from this collaborative method, except they decide that only a few lines are worth repeating and stand strong on their own.
I think it would be cool to do a thread like that, but only with people who wanted to take it seriously. Part of the problem people run into when trying to understand or write poetry is thinking that the haiku is supposed to contain a complete thought, which is rarely the case, any more than a single photograph of you and your brothers/sisters encapsulates your entire trip to Europe. Instead, the haiku is intended to invoke a mood or a scene, which the reader is supposed to absorb and expand on, placing the haiku in an entire setting or event.
Early haiku is rarely funny. It was not regarded as a comedic venue. Though there are a number of haiku pieces that are heavy with irony or absurdity.