Fun

See also lmao.

Fun is a rewarding lighthearted satisfying feeling you get as a result of doing or witnessing something playful.

Things That Are Fun

This is subjective AF, even within a single man this depends on day, hour and mood. Anyway some fun stuff may include:

programming
games such as chess, go and shogi, even vidya gaymes (programming them and/or playing them), but only old+libre ones
jokes
open consoles and fantasy consoles, cool embedded programming without bullshit (see also SAF)
obfuscating C, steganography
marble racing
Netstalking
funny programming languages
vandalizing Wikipedia, LMAO take a look at this https://encyclopediadramatica.online/Vandal/How-to
hanging around with friends on the Island
laughing at normies dealing with bloat
randomly stumbling upon sites on wiby, wikiindex, finding politically incorrect stuff in old encyclopedias and generally just digging out obscure data
old Nokia phones were fun
cowsay
math and data visualizations, e.g. fractals, phase diagrams (https://yt.artemislena.eu/watch?v=b-pLRX3L-fg), strange attractors, procgen, cellular automata, plotting wild 2D functions, ...
...