No, for real. A crossover movie joining Men in Black and 21 Jump Street is really happening. Sony put it in its huge CinemaCon 2016 presentation to theatre owners and, to make it seem even more real, even gave it a title: MIB 23. MIB 23! MIB 23! It has a nice ring to it, don't you think? It does sort of assume audiences know what "MIB" stands for, and that the "23" will be an obvious follow up to 21 and 22 Jump Street. If Schmidt and Jenko get to be the next two Men in Black candidates, I'm not sure we could be any more excited.
James Bobin is reportedly attached to direct MIB 23, though there's no release date or official cast.