Our "boss" asked us to go to office on Saturday to work on something that is not part of the current sprint, but planned to be done next sprint, because we are
A g i l e

1) overtime is not agile.
2) planning several sprints in advance(scrumfall?) is not agile.

Switching priorities is fine though, but then you push something else out of the sprint. (The company i work for skipped sprints, we just keep a short backlog queue and refill it if it runs low and throw stuff out if it grows, releases are done asap (which means several times / day as most new features get pushed out in the simplest form possible and then iterated on or killed off based on hard metrics and feedback from real users)

@ItsNotMyFault I actually already finished my tasks for this sprint. I don't know what's in my boss' mind why he is rushing me to do the tasks for next sprint.

Everytime I hear agile I have a deafening orgasm.

@immutable explain to him that inserting his head up his ass would be a proof of agility

@jotamontecino from the op:s post i would assume that his boss already has his head there

Explain "boss"

Tell him he’s an i d i o t.

It sounds to me Kanban, or even Lean Software Development, are a better fit to your company. Don't try to stick to Scrum if it doesn't fit your needs, we switched to Kanban a long time ago because it fits a lot better for our organisation. At least, that's what I did at our company some time ago :)