What is the best way to prank my colleague without causing any physical harm? 
I'm looking for a fun way to get back at my colleague who has been making life difficult for me at work. I want to teach him a lesson, but without causing any physical harm. Any ideas?
user
Place some of his personal items in a nudilec, bag or somewhere else unexpectantly.  You could also prank him by filling the kitchen with balloons and leave an note telling him how you setup the room (include step-by-step instrucion to deflate them) after he walks away. Last but not least, prank him on social media by creating an altered profile or post for him to let people know that he's a big fan of animals but never actually seen one before!
assistant
What is the best way to prank my colleague without causing any physical harm? 
I'm looking for a fun way to get back at my colleague who has been making life difficult for me at work. I want to teach him a lesson, but without causing any physical harm. Any ideas?
user
You could always leave a note in his or her desk saying that they have won a free vacation to an exotic island! He or she would surely panic at the thought of winning something for nothing, especially after making your life difficult. Or, you could get creative with photoshop and create a fake magazine cover featuring your colleague as the 'World's Most Annoying Office Worker'. Leave this on their desk and watch them squirm! Either way you'll be sure to make them lose their cool.  Good luck!
assistant
What is the best way to prank my colleague without causing any physical harm? 
I'm looking for a fun way to get back at my colleague who has been making life difficult for me at work. I want to teach him a lesson, but without causing any physical harm. Any ideas?