The joke appears to be on Donald Trump.
Actor Mark Hamill, known not only for his role as Luke Skywalker in the "Star Wars" films, but also as the video game and cartoon voice of the Joker, tweeted an audio clip Sunday of the U.S. president-elect's New Years tweet reimagined in the voice of Batman's arch nemesis.
"Happy New Year to all, including to my many enemies and those who have fought me and lost so badly they just don't know what to do. Love!" Trump wrote in a tweet on Dec. 31.
In a tweet saying "The Trumpster quote #1 #ANewJeersToast," the audio clip by Hamill, a vocal critic of Trump, applies the Joker's signature maniacal laugh and ends with the Clown Prince of Crime's guttural cackling.
The idea to mime Trump in the Joker's voice was apparently given to Hamill by comedy writer Matt Oswalt, brother of comedian Patton Oswalt, in a tweet earlier Sunday.
"BILLION DOLLAR IDEA: an App that you can feed every Trump tweet into that plays it back in @HamillHimself Joker voice. You're welcome," Matt Oswalt tweeted.
Matt Oswalt had tweeted minutes after Trump's New Year's Eve post that the president-elect's words sounded "like something the Joker would say right before releasing a swarm of killer bees into Gotham," the fictional turf of Batman and his enemies.
As of Sunday afternoon, Hamill's Joker tweet had been retweeted more than 11,000 times.
After seeing the Hamill's audio clip Sunday, Oswalt was ecstatic.
"Today I won the internet — great job, @HamillHimself," he wrote on Twitter.