When Cartman and his family end up stuck in South Park due to the discovery of a new COVID-19 variant, his kids including Hackelm plead with Kyle to let them stay at his house for the night, which he allows.
Later on, when discussing Kenny's death, Kyle gets angry at Cartman for making out with his wife causing Hackelm to yell "Fuck you, Kyle!" which Cartman chastises him for. Cartman then tries to get Hackelm to correctly say "Uncle Kyle", with several failed attempts of him saying "Fuck you, Kyle!", but declares that Hackelm is doing better when he says "Fuck you, Uncle Kyle!"
In South Park: Post Covid: The Return of Covid, Hackelm allows Eric's plan to continue as it originally planned after Eric gives it up. He calls out in the church, "Haha! Fuck you, Uncle Kyle!", and pulls the lever of the time machine.
Hackelm has short, curly, light brown hair and thin light brown eyebrows. When being held by his mother, he is wrapped up in a light blue blanket with a gray trim while he wears a red and blue onesie while inside his baby carrier. He is also seen sucking on a blue pacifier with a doll of Clyde Frog on it. He behaves like Younger Eric as he slurs at Kyle.
- "South Park: Post Covid (2021)". IMDb.com.