It's almost 10 pm now. For some reason, I have a sudden strong urge to code something till morning. The problem is I don't know what to code.

Build a simple os maybe?

Search engine

I feel you. Get that a lot. It’s like you suddenly get this urge to make something and the need to write some code, but then have absolutely no idea what. And every side project idea you have would require a lot of a priori planning to get done before actually getting your hands dirty so all of those are out of the question since you just wanna get on with writing them codes... so frustrating. Writing a small kernel did it for me yesterday, tho. So something like that is good. Something you can kind of just grasp the blueprint from somewhere and then just get going from there.

A sex robot.

@Posix That's what I did xD.

@volttide @halfflat @ScriptCoded All these are really cool ideas however, just like @100110111 said, they require a great amount of planning and learning which is a good thing but not things that you can code right away at night.
I don't know. Maybe I lack the motivation to do all the planning.

@Posix is that a posix way of handling this

If it's just code, you can do competitive programming.

@theabbie I do competitive programming but it's no fun to me.

I smell Adderall

Try to start thinking in terms of filling a need somewhere like a niche.

Example: sometimes I need a thumbnail generator but it seems they are all stuck in 2009 or something. Gotta be someone that can update the niche.

The web is filled with sites that had their time in the sun, but clearly have not kept up. All good candidates to clone and improve.

Who knows, it might take off, simple saas apps can make a lot of money on autopilot

Fill a well defined need. Do it better than the rest in the niche. Dont break new ground just find bad software and improve on it.

Hope this helps turn your hobby programming into money.