Complain about not being able to relax on the bed (to Try for a Baby)... when the bed is less than three feet away from them. And for extra stupidity points, they assume the bed is upstairs.
Adults being unable to pick up a toddler if they are beside the stairs.
Adults taking a sleeping toddler out of bed after I told them to put them in the bed two minutes ago because the child was tired just so they can tickle them.
If there was a way to punish Sims for their stupidity without killing them, I would.

Punishing them is even more of a waste of time than punishing human beings for stupidity is. They're not stupid; they're limited by the program's access faces. Learn to understand how that works, and you'll find them much easier to deal with.

The same could be said for humans as well, but then where's the fun in that?

Where's the fun in punishing people? No profit in it, either. Learn how things work and accommodate yourself to that, you get along fine. Insist that things have to work a certain way and try to force things and people to accommodate you = lifetime of frustration and disappointment.

It bugs me that a sim will often leave a computer after doing a task, so if you want to queue computer actions they keep getting up and down for them.

Or rather than smoothly transition from one action to the next, they get up, put the newspaper down on the nearest table, pick it back up, and sit down.

Sims do stupid things?

Of course Sims do stupid things. It's Life Simulation after all. If wouldn't be much like Real Life if they acted sensibly all the time, would it?

My Sims really aren't stupid. They don't do nearly as many stupid things as I do. In fact when I have a difficult decision to make, (at least in my imagination) I ask my Knowledge Sims. I can rely on them to think things though rationally and logically.

And that is the reason for my question - I, too, am quite capable of doing a lot more stupid things than my Sims do!

At least in Sims 2 you can quit without saving. It is not possible in RL.