Randy and his "disease" of alcoholism In "The Red Badge of Gayness", "Clubhouses", and "The Losing Edge", it was hinted that Randy has a drinking problem. Cartman also mentioned it in the episode "Grey Dawn", at one point stating, "Looks like Stan's dad's been hitting the bottle again." His problem was more closely examined in "Bloody Mary" after he was pulled over for suspicious of drunk driving. He got a DUI and his driver's license was suspended. The judge made him go around schools including South Park Elementary to explain to kids why heavy drinking is bad, and sentenced him to 2 weeks of Alcoholics Anonymous meetings. As a result of the A.A meetings, Randy misunderstands the concept of alcoholism and believes that only spirituality can cure him of this. He has been depicted as everything from a casual drinker to a heavy alcoholic. He still isn't as bad as Kenny's father, Stuart McCormick, as, unlike the latter, he is sober most of the time. He also had a job until he got himself fired in "About Last Night..." for a drunken tirade directed toward his boss. (It was revealed, though, that he was re-hired as a geologist in "You Have 0 Friends"). It appears Randy Marsh is a binge drinker - one who stays most of the time sober but drinks heavily at suitable instances. He might have a family history of alcoholism because his son Stan was seen getting drunk in order to avoid his cynicism in "You're Getting Old". It may be that Randy had the same problem Stan had and that Randy was constantly drinking to avoid hallucinating and seeing the entire world as a huge mass of excrement. This might mean that Randy was also diagnosed with cynicism and that his immature and dumb behavior might have been caused by the side effect of the alcohol he was consuming to cure him of his cynicism.
He was shown to still have a drinking problem in Freemium Isn't Free and Stunning and Brave although he denied this in both cases.
He appears to be extremely drawn to marijuana, going as far as to intentionally giving himself cancer just so he could get his hands on legal marijuana. He tried many ways to get cancer, such as smoking, getting a tan, and attaching cell phones to his face. He eventually came up with the idea of sticking his testicles in a microwave, as seen in "Medicinal Fried Chicken", just to get weed. Ten other men, including Jimbo and Ned, soon follow Randy's example.
Despite being drawn to marijuana in aforementioned episode, he seems to display some level of contempt for it in "My Future Self n' Me", as not only do he and Sharon hire someone to scare Stan from drugs, he also is the one to defame marijuana at the end. However, it's possible Randy simply does not want Stan to end up like himself.
It appears Randy Marsh is very musically talented. He is a good singer and he can play guitar really well as seen in "Guitar Queer-O" and "Over Logging". He also sung and played the guitar in "You're Getting Old", but this was not a display of good talent.
In "Something You Can Do with Your Finger", it's revealed that Randy was part of a boy band in the 1980s called "The Ghetto Avenue Boys." His group was successful for a few years, but he and the other members were quickly replaced due to getting "too old."
Randy began performing again in "You're Getting Old", presumably out of a midlife crises but quit because it was casing trouble in his marriage. He performed "tween wave" in Mick's Bowling under the stage name Steamy Ray Vaughn.
As shown in "The Cissy", he eventually achieved success as Lorde, although in this case it was due to his voice being changed with computers although it was implied in "Handicar" that he also plays guitar in Lorde's music. He eventually ended his music career in "#HappyHolograms", after an embarrassing live performance at The Pepsi Center and becoming disillusioned with the music industry and their use of holograms.
It is also implied in "Die Hippie, Die", that Randy and his wife, Sharon used to be Hippies, and they met at Woodstock in 1969. If this was the case, though, they would be in their mid-forties to mid-fifties. But Randy stated in one episode in Season 9 that he was thirty-five years old, so this may have been simply a cutaway joke. Also, Randy and Sharon were revealed to have met in a tree-fort playing Truth or Dare, in the episode "Clubhouses".
Randy tells the other adults in town, at the end of "Child Abduction is Not Funny", that he studied Mongolian in college, possibly minoring in the subject. He then speaks it to the children, who have joined a tribe of Mongolians. However, it appears that he doesn't apply his knowledge of the language to his life, as this is the only time he is heard speaking it. He may also have a PhD in Geology as he has been called Dr. Marsh on two separate occasions (although one of those times was himself).
In "Make Love, Not Warcraft", Randy makes a World of Warcraft account (which is named Falcorn and is a level 2 human hunter, which is not possible in the actual game at the time of the episode's creation) after seeing his son Stan play it.
In "Pinewood Derby" he makes Stan cheat in his derby race, accidentally discovers warp drive, and consequently becomes first contact for aliens coming to Earth. He and the leaders of the world keep trying to cover their lies. He grounded Stan for telling the truth, however, he and the others lied to the aliens. As punishment for failing that test so badly, Earth and the Moon are permanently enclosed in a gigantic, cubical force field and isolated from the rest of the Universe — to which Randy says, "Well, that sucks."
Randy is named after, and based upon, Trey Parker's father, Randy Parker. Randy Parker is also a geologist.
Randy has driven red sedans, Lexus RX300s, and Lincoln Navigators. In "Smug Alert!", he is seen driving a Honda Civic Hybrid.
Randy is a geologist. He also serves on the City Council. Randy has had numerous other occupations throughout the series.
In "Something You Can Do with Your Finger", Randy reveals to Stan that he was in a boy band when he was eighteen, after having been in a choir during high school. He was so eager about this new career, that he dropped out of school, left his girlfriend and his family, and immediately joined a boy band. The name of his band was The Ghetto Avenue Boys, which is meant to be a parody of The Back Street Boys. They had a hit single, "You Got It", and they made millions, living in a big mansion with dozens of women sharing his bed with him at once. But one year later, all of the group members were fired for being too old for a boy band, despite the fact that Randy was only nineteen at the time. Randy was in debt to the studio, and in order to make up for it, he had to give up all of his possessions. He then returned home at last, and used up what money he had left resuming his education. An interesting thing to note is that Randy is shown to be very proficient at the guitar in "Guitar Queer-O". He also mentions in that episode that he knows how to play several famous rock songs on the guitar, such as Carry On Wayward Son by Kerry Livgren.