Happy Time Harry is a doll Frylock buys for Meatwad during Dumber Dolls because his $3.99 price tag is much lower than the $149.95 Jiggle Billy that Meatwad wants. He comes with red dancing glitter shoes and "Action Bills", sports a missing hand with a switch blade hidden inside it, and is clothed in nothing but soiled boxer shorts. His face, personality and voice seem loosely based on actor Jack Nicholson, leaning more towards his role as Jack Torrance in the 1980 Stanley Kubrick horror film, The Shining.

Happy Time Harry, contrary to his name, is intensely bitter, nihilistic and suicidal as well as a self-abusive alcoholic and a paroled criminal; he admits to having half of his liver removed, which should prevent him from drinking, but he still does, and references his parole officer and inability to pay his bills on several occasions. His first interaction with Meatwad is to demand "pills", a request that Frylock doesn't take seriously until he begins ranting about the misery of his life. When left alone in the house, he steals Frylock's Triple Sec and gets drunk, eventually vomiting all over Meatwad's room. Despite his cheaper price tag, Frylock quickly regrets buying him for Meatwad, as he manages to corrupt and depress everybody he comes in contact with, even the naive Meatwad and the perpetually upbeat Jiggle Billy, who Happy Time Harry manages to goad into a suicide attempt in just a few minutes by pointing out the meaninglessness of his life. His total nihilism even scares the basically amoral and cruel Shake, who threatens to burn Harry like Meatwad's other dolls, only to have Harry douse himself in gasoline to "ease the prep" and dare Shake to light him up; Shake leaves by quietly saying he thinks he should "go pray". Frylock eventually threatens to kill Harry, but Shake points out death is what he wants anyway, so he ends up throwing him off a cliff in an attempt to make him immortal like in The Highlander (although Frylock points out there's only ONE Highlander, and that was a movie besides).

One would assume that Happy Time Harry was dead, however, he reappeared on The Last One as one of the villains summoned to the meeting. He seemingly kills Travis of the Cosmos with his knife and is one of the few villains to survive the meeting, eventually being blasted into the air by Frylock's eye lasers at the end of the episode.

Happy Time Harry returns in the spin-off AquaDonk Side Pieces. Where in the ninth episode, "The Dumbest Doll of All" it is revealed that after he was thrown off that cliff by Shake back in 2004, one of his legs knocked off in the fall and he got stuck at the bottom of it for 18 years, he is then picked up by a seagull, and after he tries to get it to eat him, he stabs the seagull's eye and falls down to a busy street where he is run over by a few cars, but to Harry's dismay, he still dosen't die, so he grabs onto one of the cars and tries to shred himself to death, but even that fails. Now without his entire lower half, Happy Time Harry goes to the Aqua Teen's house to get Shake to kill him, since he now thinks he actually became a highlander, and they both know the only way to kill a highlander is by taking it's head off, but after Shake takes his head off and he still survives, he gives up and throws Harry on the ground, making him explode and finally giving him the death he craved for so long.