It’s meta-fun because you’re getting fun with the mean rather than the end.

To me, it’s fun to achieve a goal — programming to solve a real problem, implementing something that I can use or others can. It’s super fun when my program works, has no bugs, it’s cute and nice.

To others, the act itself of programming is funnier than actually doing something useful, so that you can deep dive into the best way of programming without actually doing something useful if not a program complex enough to use whatever programming feature you want to have meta-fun with.