There is of course a fine line between ‘harmless prank that may be enjoyed by the victim’ and ‘cruel trick’, or even ‘harassment’. Optimally, a good prank should be reversible within ten to fifteen minutes, and should not require any serious conversations with the boss and/or police. If the target laughs until they pass out, it’s a good sign.
I found out once that a friend of mine has a heart condition *after* setting off a loud explosive surprise for them - one of those little ‘toilet seat’ cap-snap devices, placed under his book. Thankfully, he didn’t keel over and die.
I’ve not done anything workplace-prankish, though I did wear a silly hat this last april fool’s.
My favorite prank is to tape newspaper over someone’s door in the middle of the night. When they go out the next morning, they are confronted by yesterday’s news. I have also successfully ‘forked’ a friend’s lawn. Get a bunch of plastic forks, and place all over the lawn, tines in the ground. it’s good for a great ‘WTF?‘. They’ve never really determined it was me to their satisfaction.