One of the best things about Derek was his inclination and ability to lighten the mood of a friend. Witness this example from Liz Stewart:

Derek, myself, truss perhaps, and other people were sitting at the
wedgeterms (the current location, not the old location near the
mailboxes), I assume waiting to log in.  Derek and I were sitting 
in chairs, facing one another.  I was ranting and raving about
something or other, and is my usual, I got a bit...general with
my cursings.

"Yadda yadda yadda, yadda yadda yadda, people are assholes."

Derek, upon hearing this, reaches over and takes my glasses off of my
face.  This was a bit unexpected, of course, so I watched him as he
put my glasses on his face, leaned back in his chair, folded his arms
over his chest and said, "People...are assholes!"

At which point I just about fell out of my chair laughing because he
looked so utterly ridiculous wearing my glasses while trying to
imitate my ravings.