How do you deal with estimates?

One of the scariest things to reply back to another human being a Software Developer is the dreaded question:

"How long is it going to take?"

We all hope we could answer "Whatever it takes" to our managers or bosses, but we need a stable income in our lives.

Some people come up with arbitrary times, whether it's a few days, a week or two, maybe 3... but we can all agree that overshooting and getting it done sooner than expected makes us look way better than undershooting and responding with the classic:

It was more complicated than what I expected...

Some people prefer using points systems, others might argue that time intervals might be better... But ultimately, we can all agree that we all, as human, are pretty terrible at estimating.

So, how do you do it?