Create a joke with a central subject being the SDMB itself. I’ll start.
How many Dopers does it take to screw in a light bulb?
Three. One to screw it in, one to ask how it was done, and the third to provide a cite.
I like yours. I’m gonna modify it.
How many Dopers does it take to change a lightbulb?
Four. One to get a ladder, one to buy the bulb, one to screw it in, and… Hi Opal!
What did the blonde Doper say when asked about the possible link between hair color and intelligence?
A link to a study proving there to be no relation! 
A Doper, 4channer, and a IMDBer are sitting in a psychiatrists office.
The IMDBer says, “I can tell you everything you ever wanted to know about Citizen Kane, about the angles used, the history of the character, how much of it was Autobiographical to Orson Welles. Anything.” The Doper and the 4channer nod approvingly.
The 4channer says, “I can tell you anything about any anime title ever released. From Ultraman, Devil Man, Gundam, Tenchi Muyo or any other series to tentacle sex or catgirls.” The Doper and the IMDBer also nod in approval.
The Doper looks at his reflection and comments, “I’ve got to stop reading so many frickin boards!”