alias crontab='fuck you, <insert name of colleague here>'
Everyone knows that in a [in]sane workplace, you ALWAYS have to lock your machine. So this particular new hire forgot to lock her machine and one of the seniors (senior prankster, I would say) jumped into her terminal and set a crontab to run EVERY MINUTE.
So she comes back (we pair program so they were actually pairing that day) and goes on with programming for a few seconds. Then she tells us to be quiet. We're all like "WTF?"
She asks, "Do you hear some robotic voice saying something?"
At this point we're all trying to listen but to no avail. She thinks it's her machine (which was connected to a 27" monitor) and proceeds to max the volume. A few seconds later, the whole office hears a thundering robotic voice say "ASSHOLE".
Everyone laughs. From that point onwards, we all had shortcuts to lock our screens, and as an added "security" feature, we aliased our crontab to actually say "fuck you" to our senior prankster.
I would then set their .zshrc or whatever to end with
echo "sleep 0.1" >> ~/.zshrc
Now my favourite part was that I edited the oh-my-zsh update script to actually echo the original echo line into their ~/.zshrc file, so that even if they figured out what was happening and were very vigilant with locking their laptop, it would happen again within the next 14 days. Loved that.
It took the victim so long to figure out what was causing it, that it made it so much funnier.
say 'fuck you, <insert name of colleague here>'