This show is the stealth bomber flagship of this trope. On more than one ocasion the word cunt, which is not allowed to be broadcast on network television, was alluded to and actually said once. See Last-Second Word Swap on the main page. Also when Tobias tells the cockney cab driver to take him to the "Gothic Castle" the cab driver replies "Gothic Asshole?" and takes him to a gay leather bar. Even though the word asshole isn't allowed by the censors, the driver's cockney accent gave the impression that he simply repeated Tobias' line back at him.
The episode where a close-up picture of a scrotum was shown repeatedly.
In a brilliant example, one episode managed to get the word "fucking" aired by splitting the word in half, and airing the second half ("cking") 5 minutes before the first half ("fu"). Put together, the full quote is "No Al, I want to spill booze all over my fucking $6300 suit! Come ON!"
Another episode showed GOB exhaling what was obviously marijuana smoke without showing him actually taking a drag.
And letís not forget about Buster's uncensored "If mother sees this, she will blow a cow". note Actually, in the DVD commentary, series creator Mitch Hurwitz notes this is a little stealthy joke: The narrator points out George Senior slips by the sensors (by crawling into a duct that he had discovered accidentally behind the kitchen fridge) right before Buster utters his phrase.
The first episode of the third season has one that's also a Stealth Pun. It's implied that Lindsay did a Cheek Copy at a Bluth Company celebration. She shows Michael a picture of that, thinking it's a picture of a car she's interested in, leading to this exchange:
Lindsay: We did it, Mikey! We're super-rich again. And I'm going to buy a car. The Volvo. [hands Michael a piece of paper]
Michael: No, Lindsay, you're not going to start spending money. [looks at paper] And this is not a Vol-vo.
Another Stealth Pun: she later changes her mind about that car because it's "too boxy."
That whole episode is laden with innuendo. Michael in particular has some real gems.
Michael [after learning that Kitty was cheating on Tobias with a Blue Man]: It all makes sense now. Dad's in Reno, Kitty's in Reno, Dad's in Kitty, and Dad's a Blue Man.
This is also the episode with Swallows, "a family-style restaurant by day and an anything-goes pansexual bazaar by night" featuring all manner of fetish gear (that isn't shown on-screen, but frequently alluded to).
Lucille, referring to the cornball-making machine, uses the word "cornholing."
Tobias has many, including "teabagging" and "Uncle T-Bag". Actually any of Tobias' unintentional double entendres qualify since they're made without the character's knowledge.
Tobias: I'm afraid I just blue myself. context While covered in blue paint for his role as an understudy for the Blue Man Group
Tobias: I figured if I blue myself early, I'd be nice and relaxed for a 9 o'clock dinner reservation.
When talking about the summer home on wheels:
Michael: Maybe you can take a date up there! Lucille: How am I supposed to find someone willing to go into that musty old claptrap? (incredibly long awkward pause) Michael: (suddenly) The cabin! Yes. That will be difficult, too.
There was also the time they managed to actually get Rita to call Michael a 'pussy' because it was actually a British word for a kind or gentle man". note It's not, but it let them get it on the air.
Narrator: I can't believe we had to censor that. It would have been such a nice moment.
Michael: Since you're devastating people, why don't you go tell Gob that I'll be telling the cops that it was him in the truck, so he'll be joining me here. I've got a nice, hard cot with his name on it.
Lucille: You'd do that to your own brother?
Michael: ...I said 'cot'!
When Michael has demonstrated concern for his mother as she prepares to seduce the prison warden:
Lucille:I want to cry, but...I don't think I can spare the moisture.
Maeby refers to the so-called Mrs. Featherbottom as Mr. Fingerbottom.
When Lucille enters while Gob and Michael are arguing about Gob's recent purchase of a boat, The Seaward:
Michael: Get rid of the Seaward.
Lucille: I'll leave when I'm good and ready.
When Michael hires his prostitute possible-sister to work at the Bluth Company, he calls to check what the employees think of her.
Michael (On the phone): Well, you forgot to say "away." (To Lindsay) Nellie is blowing them all away.
From the finale, Tobias has hired the Hot Cops (a troupe of male strippers) as entertainment for a party on a yacht.
Tobias: I'll tell the Hot Cops to come up with something more nautically themed. Hot sailors, or better yet, hot sea--
Michael: Uh... I like 'hot sailors'.
Tobias: Me too.
Narrator: And George Michael was about to encounter a hot sea-man of his own.
Later in that episode, Lucille tries to get the Hot Sailors to help her escape by running the yacht's engines.