I also work with this guy, Mark. He goes by the nickname "Horsehead." I've tweeted about him in the past - mostly about not knowing how he got the nickname. I recently found out how Horsehead got his name. It's not very interesting, so I won't bore you with the details.
Below are some videos of Horsehead. Alcohol is involved in all of them.
Horsehead gets a haircut
Horsehead (with an assist from Bob at the end) pays tribute to Billy Mays.
Horsehead gets drunk, puts on an afro wig, and lip synchs a motown hit.