In the episode where Rocko and Heffer go to the gym, there's a scene where Heffer was sitting at a weight training station with his back to the camera. All we see is his arms moving back and forth. A woman comes up and asks if he needs any help, to which he replies. "Yeah" then holds up a plate, a pair of chopsticks, and says, "These plastic things can't cut my burrito."
The same episode also has Rocko using a virtual rowing machine. Rocko chose The African Queen, but the machine immediately went to Deliverance, complete with "Now, we're gonna make you squeal, piggy!" (thankfully on RML, it was making a pig laugh by tickling it with a feather).
One episode involved Rocko chasing a bird that kidnapped Spunky. The bird flies over a nude beach. Rocko slips out of his swim trunks and goes in (but not before a blue-shaded censor slaps a black box over his butt).
In "Bedfellows," Heffer throws a nudist party with Bev taking a perverted interest in it (and even had her own at the end of the episode).
In the episode "To Heck and Back," Heffer goes to Hell. In Hell, there is a sign that has the word "HECK" on it. Underneath the C and the K, there are Ls. Then, when Heffer corrects Peaches about where he is, Peaches slaps a hand over Heffer's mouth and says, "Censors!".
"Flu-in-You-Enza" featured a scene in a hospital, where a call for "Doctor Philiac, Doctor Ned Crow-Philiac" is heard.
Also in this episode, the crazy doctor Ben Dova (who, according to the hippo nurse, is a mental patient who was supposed to be strapped to the bed) cupping Rocko's eyeballs (as one would do with testicles) and asking him to cough, then doing something to him that involved a rubber glove and ended with Rocko walking shakily out of the doctor's office. Later, Dr. Dova appears as a pro wrestler, and is introduced as "the proctologist of pain".
The bluejay smoking in the waiting room, then coughing up his heart and dying on "Flu-In-U-Enza." The radar pretty much said, "Screw it!" — and this was only in the third episode.
In the premiere episode "Sucker for the Suck-O-Matic," right after Rocko, Heffer, and Spunky leave the house, there are naked fairies flying around some flowers. When the Suck-O-Matic sucks it up, a fat, shaved gopher in underwear is seen holding binoculars, looking up and panting.
One bit has Rocko pointing at a rebus-like design that shows a dog minus two baseballs as he says, "We'll try the neutering function later."
In the episode where Rocko tries to get a good picture of himself for the newspaper (to get a promotion at his job), he enlists Filburt to take the picture of him. Before Rocko and Heffer enter Filburt's trailer, several women leave (and all that's shown are their legs). When Heffer comes in, he says, whilst blushing: "I spilled my puffies..."
It didn't help that said women's legs had the uber-high, Jessica Rabbit-esque high heels... and they were followed out by a pair of bare rabbit legs.
Hef's grandfather's insistence that Rocko is a beaver, particularly in this line: "Ah, 'coyote', eh? Well, ya can't fool me. I can smell a beaver from 30 miles away — beaver."
At the dinner table he yells, "I say we eat the beaver!"
There was also the recurring joke of Heffer's stepbrother, Peter, being Ambiguously Gay— like in his introduction episode, where he is seen going to cheerleader practice dressed in a female cheerleader's outfit, and his father screams while his mom says, "We were afraid to tell you." Then on the episode where Heffer is chosen to go through his manhood rite of passage, Heffer asks his dad, George, why Peter can't do it. Peter sarcastically replies, "Oh, yeah, like I'm really gonna do it," then adds, "I'm going out." George suspiciously says, "Where are you going?" Cut to Peter in a tutu and ballet tights, grumbling, "Here we go again: judge, judge, judge."
While nearly the entire episode "Leap Frogs" was this trope (at least before it was pulled from rotation, though it's now on Netflix and the Shout! Factory DVD set), pay attention to the nature documentary Bev and Rocko watch near the beginning. The female frog in that show has breasts with nipples in plain sight.
Throughout the series, the main characters' favorite fast food chain is called "Chokey Chicken"◊ — until season three, when the censors finally caught on and changed it to "Chewy Chicken."
In the episode "Canned," one of the jobs Rocko takes on is that of a "specialty phone operator", which turns out to be a phone sex line, portrayed by him on the phone saying "Oh baby, oh baby, oh baby" in an unenthusiastic monotone to somebody on the other end. This was made even clearer by a poster hanging in Rocko's cubicle reading "Be hot, be naughty, be courteous", and made clearer still when they showed both his and Mrs. Bighead's Oh Crap reaction when they recognized each other's voices (and with them both immediately hanging up).
On the episode "Canned," Rocko's first job after he gets fired from Super-Lot-O-Comics is a tattoo artist where he gets swallowed by a rhino known as Mr. Horny note (For context: Rocko was tattooing a can of beans on the roof of the rhino's mouth and he kept getting queasy). Yeah, that doesn't sound wrong out of context...
"Closet Clown" was just one big Does This Remind You of Anything? that shows Ed's clown obsession as either an allegory of being a cross-dresser or being a homosexual.
In once scene from the camping episode ("Hut Sut Raw"), Rocko is seen picking berries from a bush and then accidentally grabs a bear's genitals. Sadly, this was one of many innuendos that only made it past the radar the first time around. The reruns in America have the scene cut just as Rocko is about to pick the berries from the bush, but a lot of overseas airings (some of which from countries where the censorship is a lot tighter than what America dishes out — i.e., the UK and Australianote Just look at how they edit Adventure Time and Regular Show for a glimpse at what they find offensive. Some of it is in compliance with what America would find offensive for kids shows on TV; others go by their own rules and beliefs) have the scene uncut.
The episode "Schnit Heads" (which, much like "Who Gives a Buck"note pun on "Who gives a fuck?" and "Carnival Knowledge"note pun on "carnal knowledge," which is just a fancy way of saying, "sexual intercourse", is a very dubious pun that no sane kids' show would consider using for humor) is basically the writers saying, "Hey, how much sausage innuendo can we get past before the censors notice?" as well as an old-school Simpsons-style satire on organized religion (or cults).
The Credit Card Plot episode "Who Gives a Buck?" — of which the title itself is questionable at best — features Heffer watching a television channel called 'The All Scottish Show'. When the name of the show appears on the screen, the acronym it forms can clearly be seen.
In the same episode, when Rocko has to buy Spunky a new dog bowl, the sleazy salesman invites he and Heffer to take a ride on a train through the store with the stipulation that they must "sit" "Doggy Style."
In "Rocko's Happy Sack," during Rocko's tirade about how he went through hell to beat the supermarket sale deadline and should pay the $1.50 for groceries instead of $150.00, one of the things he mentioned is being "threatened by your Gestapo security guards" (even though that scene never appeared in the episode). Kinda tame, but these days, you'd never see a Nickelodeon cartoon make a light reference to Nazi Germany (the Gestapo were Hitler's secret police force).
In the episode where all of Ed's bugs crash at Rocko's house, there is a scene where a female caterpillar turns into a butterfly. Her boyfriend then turns into a screw, symbolizing that he got "screwed" over.
In the episode where Rocko watches Filburt's bird, the bird snatches off Mrs. Bighead's bikini top, causing her to smile suggestively and say, "Such a naughty bird".
The same goes for Grandpa Wolfe's "racism" toward the "beaver" (Rocko) (and how Heffer can't tell Grandpa Wolfe that Rocko is a wallaby, because Grandpa Wolfe hates wallabies as much as beavers), reflecting the inbred racism in old folks.