I like horrible jokes and puns. I especially enjoyed making up Dad Jokes to torture my family over the years. I finally hit upon the idea to collect a bunch of "open-source" jokes, add in a bunch of original jokes that I would write, and send it out to several niche publishers.
I decided to go with Yo' Mama jokes because they were worth a good chuckle and, if I kept it relatively clean, could be sold to kids. I collected a large volume and then wrote over 250 new ones. I shopped it around but none of the small presses were interested. Well, I could have posted one a day on my blog just for fun but I didn't want to waste all of that effort. I went ahead and put out a print trade paperback and published it in 2012.
For some odd reason I sell a bunch of them around Christmas. I also sell a lot of copies when I sell books at conventions, usually to parents who want to get their kids something that was inexpensive (eight bucks), good for them (books are books), and so they could feel better about buying a samurai sword stuck into a two-foot metal dragon skull.
None of the publishers wanted to take a chance on a joke book, but it ended up pushing me to go from traditional to hybrid (trad and self) publishing. I got to keep all of the money and I went ahead and did some projects I had on the back burner, including publishing some pulp science fiction from forgotten and long-gone authors.
All because of Yo' Mama.