Obi-Wan and Darth Vader are sitting at a table in a cantina, when a film producer walks up to them and says, "Hey, guys, I'm shooting a music video for Abba and I want to use your amazing powers with the Force to create awesome special effects."
"I'm in," says Vader.
"I'll pass," says Obi-Wan.
"What?" says the producer. "Why won't you help?"
Obi-Wan looks the producer in the eye and says, "Only the Sith deal in Abba shoots."