star-wars
Explanation
The Joke
A woman enters what appears to be a dining area decorated with Star Wars napkins and plates, and sees someone dressed in a full Darth Vader costume, complete with a glowing red lightsaber. She excitedly exclaims, "Oh, wow Star Wars napkins! And plates! And you're dressed like Darth Vader!" The figure in the Vader costume ominously replies, "We need to talk." The caption below reads: "Hot New Trend: Themed breakups."
The woman initially thinks this is a fun Star Wars-themed party or event, but the phrase "we need to talk" -- universally recognized as the dreaded opening line of a breakup conversation -- reveals that her partner has gone to elaborate lengths to theme their breakup around Star Wars. The Darth Vader costume is particularly apt, as Vader is the iconic villain who delivers devastating news ("I am your father").
The Humor
The comedy comes from applying the concept of themed parties -- a fun, lighthearted social trend -- to one of the most painful interpersonal experiences: getting dumped. The idea that someone would buy themed napkins, plates, and a full costume to break up with their partner is absurdly over-the-top. The woman's initial delight at the decorations makes the incoming emotional devastation even funnier by contrast. There is also a layer of humor in the specific choice of Darth Vader, since the character is famous for being menacing and delivering crushing revelations, making him the perfect mascot for a breakup.