"That's your Uncle Grandpa for ya. Drops in, shows you a good time, and then you never see him again. Just like your father."
Pete Browngardt originally pitched Uncle Grandpa in 2008 for the cancelled animated shorts vehicle Cartoonstitute (the same project which spawned Regular Show). When the finished cartoon was released through the Cartoon Network website, it quickly became a word-of-mouth hit within the animation community, eventually going on to be nominated for a Emmy.The character then went through a couple of years of Development Hell, only to reemerge on an episode of the equally bizarreSecret Mountain Fort Awesome (also by Browngardt). When SMFA was cancelled (or put on hiatus its not really clear), Browngardt decided to switch gears and focus back on Uncle Grandpa, expanding its cast of characters and retooling it as a Variety Show. He succeeded, and the show eventually premiered in September 2013 much to the delight of fans of the original shorts. Even Golden Age Of Animation purist John Kricfalusi seems to getting pumped for the show judging by these sketches.
Ambiguous Syntax: In one skit Uncle Grandpa asks Mr. Gus, Pizza Steve, and Giant Realistic Flying Tiger if they know how to play the drums, the bugle, and the keyboard, respectively. They reply that they don't and proceed to play terribly, then Uncle Grandpa comments that they do know how to play; he was asking them if they know how to physically use their instruments, not if they were any good with them.
Breaking the Fourth Wall: "Viewer Special" is an entire episode where the scenery itself is composed of Fan-Art, while Uncle Grandpa and company comment on how weird the episode is. A subversion occurs in that the episode is presented as a Show Within a Show, and one lucky viewer of the cartoon draws the episode by drawing his pen directly on his own TV screen.
Cloudcuckoolander: Uncle Grandpa hardly makes any sense... until he does. He once thought that the spelling of his name "Uncle Grandpa" was an imposter of him. Gus pointed out that it's only a spelling of his name, and he thinks it has magical spells, rushing off to find a way to deal with it.
The Cloudcuckoolander Was Right: In "Jorts", Uncle Grandpa sees a cactus and at first assumes it's an alien before Belly Bag corrects him. But when Uncle Grandpa pulls it out of the ground, it does indeed turn out to be an alien.
Cool Shades: Pizza Steve almost always wears his Shades. Because he's so Cool.
Cool Uncle: Uncle Grandpa is the living embodiment of this trope.
In "Space Emperor", Uncle Grandpa says "As God as my witness...". References to religion is normally forbidden in children's western animation.
In "Uncle Grandpa for a Day", one of the visuals in Uncle G's peanut butter song is him naked in bed with a jar of peanut butter.
In one episode, Uncle G and his gang end up in a sewer full of brown liquid. Everyone but Mr. Gus thinks it's root beer and starts drinking it. Apparently, it really is root beer and not something more disgusting.
Mr. Gus watching and reacting to being caught watching a program about crocodiles. His reaction to both is akin to someone watching and getting caught watching porn.
Park > Drive > Reverse > Flip > Up > Plaid > Apple Pie > Nuts > Turbo > Explode > Implode > CRAZY BABY
Portal Painting: Uncle Grandpa once accidentally created one. It was a T-shirt design rather than a painting, but still.
Raising the Steaks: "Tiger Trails" features black belt zombie pets. One of them is a pet rock.
Reality Warper: He gives Haruhi Suzumiya a run for her money. Being able to literally do anything, there's no telling just how he'll solve a problem. Sometimes it seems like he doesn't alter reality so much as reality conforms to his desires.
In "Space Emperor", the creature Melvin gets transformed into looks strikingly similar to Festro.
In "Afraid of the Dark", when Uncle Grandpa examines the poster of a knight fighting a motorcycle with a magnifiying glass and it turns into a map, it's drawn in a style reminiscent of the map screen from Super Mario World.
"Uncle Grandpa's Money Madness Spectacular" is a blatant parody of Monopoly, complete with Uncle Grandpa being in the same pose as the latter's mascot.
In "Treasure Map" we see that Mr. Gus has One Bad Lizard stitched on his wallet.
Spin-Off: A unique case of a double subversion. Uncle Grandpa started out as the star of his own pilot, then he was spun off into Secret Mountain Fort Awesome, then he was spun off again... Back into his own series.
Stable Time Loop: Apparently, when Uncle Grandpa was a kid (he still had his mustache back then), he was picked on for having a fat belly. His present self popped up and told him that it's cool to have a belly. All of this happened inside his own memories, thus he altered the past while he was remembering it.
Widget Series: From the moment Uncle Grandpa reappears in the picture frame AFTER disappearing from view from outside, and then walking into frame from the side (if not sooner), it's been made incredibly clear that this show isn't simply on a rocket train to Weirdsville, it already arrived long ago, made itself at home and set up shop.