1) keep walking and go about my business

BUT... back in the day when I engaged in juvenile pranks of this nature, I'd just open their email program, start a new email, put the CEO's email address in the TO field, and type "I resign" or something in the body, and then just walk away.

I'm a prude, so I get my coffee and go back to work.

You don't want to be known in the office as the person messing with coworker's computers. Next time a computer acts weird, a file is missing or settings changed they'll blame you.

Back in the 1980’s there was an automatic invitation to the user’s hosted party at their house.

I did that kind of thing a couple times in college, and basically got it out of my system.

Add a comment somewhere in the middle of the code they’re working on saying /* I should always remember to lock my computer */ and amend their current commit. Maybe they’ll spot it, maybe code review will notice, maybe not.

Great thread, hopefully some of us are still young and can provide an entertaining response

It used to be update keyboard language and watch as they tried to figure out what was going on. These days I walk on by.

I've never worked in a place where this sort of thing would have been tolerated. In high school, sure. But not the workplace.

Sorry past me - I'm boring now.

Pretty sure I'd get fired if I did anything with unauthorized access to someone else's machine. They might too.

Best/fun case: when I was contracting some years ago, if you had your laptop unlock someone would send an email to the project team "coffees are on me! let's pick them up after lunch", and they would pay (but everyone's daily rate was multiple hundreds of GBP per day, and that would pass as 'expense' so the total 40-50 pounds didn't hurt much).

Worse case: (same company) someone send an email to all infra team (including the VP) that "I'm stupid and I don't lock my laptop". That guy (the 'funny' one) was kicked out of the project/contract/building within the hour.

My friendly advice, lock it for them, when you see them again take them on the side and tel then "hey dude, lock that damn thing" and move on with your life.