Boneless pizzas can be found lying around just, anywhere, really. In the oceans, on the streets, in your mom, etc. The reason for this is that they are summoned at random every time someone gets a boner. Like an Equivalent Exchange kind of dealio.
They are quite dangerous, as they contain anti-bone matter, which is attracted to normal bones, and annihilates with them upon contact. For most people this isn't much of a problem, you just have to avoid eating them because then it eats your teeth.
For skeletons, or people with exoskeletons, however, it's a different story. Those guys are very concentrated and openly available sources of bone, and so boneless pizzas are very attracted to them. For this reason, many skeletons carry fake bones with them. You know the squeaky ones that you can throw to get your dog to chase them? Except in this case it's a pizza that has to chase them so it doesn't kill you. They also put these fake bones in front of their doors at night. It satiates any boneless pizzas that may come close, and it's also a pretty good intruder alarm, especially if they are imbued with hypersqueak.
You need to warn your children about these pizzas. The boneless pizza might peek out of a sewer, enticing them with promises of dank memes and pepperonis. Then they're like "Alright kiddo now just take my fat greasy calzone in your mouth and extract my meme juice." This is how they get inside of your kids. And then they steal their teeth and infect their body. Over the next couple days their skin becomes greasy, and they start speaking fluent Italian. Finally, they become a pizza. It happened to me, Pizza Boy, don't let it happen to your kids.