While Del Murder was at work, I went to the train station where he parks his car and with his spare keys, moved his car to a different parking spot. In the original spot, I left a Goomba. 
(SPOILER) 
I also covered his car with 8-bit Mario. 
(SPOILER) 
Meanwhile, I got his coworker to change the lettering on his keyboard. I also STRONGLY encouraged them to make his cubicle into a 4-walled cubicle, but they failed on that. Was majorly disappointed. 
I also put a CD of 
Do the Mario in his car's system and had it set to blast the song as soon as he started his car. 
This was all in one day. 
Another time I rubbed dye on my feet to make them look like they were rotting so that he would think I was turning into a zombie. Another time I put blue tint on my fingers and started shivering to make it seem like I was getting some crazy frostbite tit going on. 
And so and so forth. I pull a lot of pranks on Del Murder.