As Ulysses suggested in the comments of their question: TeX Art Fun - Mandalas, I think the Community should decide if fun questions of that kind (i.e. contests, social events, etc.), which require some coding, are to be asked on the Main site or on Meta. Both have occurred in the past, as shown in the examples given below.
Also, what are some good guidelines for how to set up such questions? For example, does it matter if they can potentially give reputation (to either the question or the answer)? Should they be Community Wikis? Are bounties appropriate prizes? What contest rules, prizes, etc are or aren't ok? What tags should be used? Anything else that should be considered? These don't necessarily need to be rules as such, but can be simply etiquette and the like.
A few pre-prepared answers have been provided below as a rough poll. You can upvote any you support, and/or add a new answer to discuss things in greater detail. If there is a clear consensus we can perhaps adopt this as the official rule.
Since there was a misunderstanding, the types of questions being discussed are contests and/or social events.
fun tag is used for a lot of different things, not just what's being discussed here, and we don't want to
remove it or restrict its usage.
Example of such questions on Main:
How can we display fireworks?
Seasonal Challenge (Contributions from TeXing Dead Welcome)
\pi day riddles for LaTeX users
Welcoming 2019 Pi day: How to draw the letter π?
Welcoming 2019 Lunar New Year: How to draw a (lovely) pig?
I need a TeX-donkey
Example of such questions on Meta:
Let us have some TeX-mas fun [completed]
Preparing for Groundhog Day
Note: we are not talking about questions like these (which are tagged
fun, but are not specifically contests
or social events):
Create xkcd style diagram in TeX
How to properly typeset a rolling r
How do I make my document look like it was written by a Cthulhu-worshipping madman?
funtag is used for a lot of different things, not just what's being discussed here. For example, I don't think the linked questions regarding rolling Rs or xkcd graphs fit the theme.