Dry humor with a blank expressionless face. This type of humor is common among shy and socially indifferent people. Includes other elements of humor ranging from shy humor, sarcastic even macabre humor and other personal characteristics which makes it unique to the individual. Deadpan humor is one of the most complex and to many enigmatic comedy styles as only a select few truly understand it enough to appreciate it for it's brilliance.
A friend that over the years you have become attached to for unknown reasons. It is usually someone you have invested a lot of time and money in, all in good fun, for a while. They always let you down but you can't seem to stop hanging with them or helping them. They are typically low lifers who take what they can get from anyone and leave everyone thinking they're a good friend, until they're gone.
"i thought debbie was gonna be there for me, turns out she's just my deadend friend."
"why bother go pick debbie up for the party? she's just a deadend friend."
Stephen Colbert (in ultra-serious, blank face): "I cannot see through all of this liberty."
*audience laughs*
Stephen Colbert (in ultra-serious, blank face): "Yes, I excell at deadpan humour."