Obama torched Republican Herschel Walker for a previous bizarre aside during a November rally.
Walker mused during a speech whether he would want to be a vampire or a werewolf.
"This is a debate that I must confess I once had myself when I was seven," Obama deadpanned.
Former President Barack Obama lampooned Georgia Republican Herschel Walker on Thursday night, arguing that the former football great is akin to a crazy uncle who should not be trusted with serious responsibility.
"Since the last time I was here, Mr. Walker has been talking about issues that are of great importance to the people of Georgia. Like whether it's better to be a vampire or a werewolf," Obama said during a rally to tout his support for Democratic Sen. Raphael Warnock in the closing days before Georgia's Senate runoff.
The former president then twisted the knife, "This is a debate that I must confess I once had myself when I was seven. Then I grew up."
Obama's reference to the horror movie tangent is related to Walker's bizarre aside during a November rally. The former president also poked fun at the 1982 Heisman Trophy winner for claiming he let Obama beat him in basketball before conceding that they had never met.
"I don't know if you know, but vampires are some cool people, are they not?" Walker said. "But let me tell you something that I found out: A werewolf can kill a vampire. Did you know that? I never knew that."
Democrats are already guaranteed to have control of the US Senate as a result of the midterm elections, but the outcome of Tuesday's runoff will determine whether the chamber will remain evenly split or if Democrats will hold a 51-49 majority. Obama stressed that beyond the real impacts of an extra seat, Georgia can't afford to send someone like Walker to Washington.
"This would be funny if he wasn't running for Senate," Obama said. "We all know some folks in our lives, who we don't wish them ill will, they say crazy stuff, and we're all like well, you know, Uncle Joe, you know what happened to them ... They're part of the family, but you don't give them serious responsibilities."
Obama wanted to make sure that people knew Walker ultimately decided that he would be a werewolf.
"As far as I'm concerned, he can be anything he wants to be besides a United States senator," he said.
A representative for Walker's campaign did not immediately respond to a request for comment.