Plug a wireless mouse into the back of his computer. jostle it occasionally so he thinks his mouse is on the Fritz. Slowly add pennies to his desk phone every night till it's really heavy then take them all out and watch him hit himself in the face. shift everything in his office/cubicle to the left a few inches and watch him go nuts trying to figure out what's wrong. Crush up melatonin into his coffee so instead of getting a caffeine jump his body tries to put him to sleep. (melatonin is a natural body produced sleep aid you can buy at any Walgreens)

find out what TV series he's currently watching and viciously spoil everything.

I guess that's one reason Dave lost the Chipmunks

God dammit,Dave!!!

What are you doing, Dave? (if you have seen Airplane II, you will get the reference)

Sounds like Dave had a nice lunch

What the hell is furry ****, I'd google it but I'm currently at work on break

Pin Justin Bieber's picture in his cubicle or set it as the wallpaper and lock screen on his computer. If you can set some embarrassing ringtone on his phone then it'll be hilarious. :-))

**** you dave

I hope they tell us when and how they get Dave back.

Dammit, Dave. Never let a coworker use your computer. Kindness doesn't always pay off.

I think we found out the reason why his work computer was acting funny.