Should we ask to add a close reason for purim-torah-in-jest? Admittedly, anything we do on that front is a hack to the system.
There was some discussion of this (which I can't find now :-( ) when we got the custom close reasons. On the one hand we need to be able to close the purim-torah questions with an appropriate reason each year. On the other hand, we don't really want extra close reasons cluttering up the dialogue the rest of the time (it should be as easy as possible for people to choose appropriate close reasons).
We actually have this close reason, but it is not currently activated (meaning you don't see it in the close dialogue). Since we can activate it at any time, we decided to try leaving it inactive for most of the year, activate it for that one batch of closings each year, and then deactivate it again. With luck that will meet everybody's needs. If somebody asks a purim-torah question out of season, just close as off topic (and, if you can, leave a comment suggesting the person come back later).
Since few purim-torah-in-jest questions are asked for most of the year, most closures for that reason are all at once when the season is over. These are easily handled by a moderator, who can copy-paste the reason as a one-off off-topic closure reason even without activating the custom (but non-one-off) closure reason.