Playing around with the keyboard keys
One of the most classic pranks you can play on a coworker is messing around with their keyboard. You can be creative by plugging in a wireless keyboard dongle and controlling typing in random stuff from afar. But the most basic prank is simply by switching the positions of every key.
However, if you don’t memorize where the keys go, this can cause some trouble later on. Of course, you can look on Google for where the keys go in a standard QWERTY keyboard, but this person felt they had to disturb the office’s IT guy. Or maybe they couldn’t type in Google because they forgot where the keys were.