One of my favorite "under the radar" moments was in an episode of SpongeBob where they showed someone robbing a bank, and the robbers started screaming "ATTICA! ATTICA!" like in Dog Day Afternoon.
That's not under the radar as much as it is a pop culture reference.
I love how 4Kids snuck some pretty adult jokes in their dubs of Ultimate Muscle and the ill fated Funky Cops. And this is, mind you, a company that's at the mercy of American TV rules and Bowlderizes the heck out of everything so they recolor guns to look like toys, don't state than any character is dead, and goes out of their way to make cartoons safe for prudish old grannies while ticking off everyone else who's mature enough to know about violence and death... anyone in the actual 6-10 demographic.
BUT, they managed to slip a couple really questionable lines in UM...
"Roxanne and her friends can join me. We can have a foursome... for GOLF!"
"There's somethin' in the Kid tonight. And I know it isn't Steroids, cuz his urine tested clean."
"The rope stretches like a G String... of a guitar."
And on Funky Cops, a sequence where a really nasty ship's crew member hands a disgusting cocktail out...
Woman: it looks like some sort of Witch's Brew!
Ace: Rhymes with Witch
And of course an episode where Jack said something about getting his partner an "Inflatable..." for his birthday. Pretty dirty stuff considering how hard this company censors stuff.
Oh yeah me too, when they're under the radar. It's when they start to lose their subtlety that things get ugly.
But the thing is, an adult show doesn't need to hide anything because the audience knows what they're talking about. It looses a lot of that clever sneaking around, though. I agree I liked it better when they implied that Ren and Stimpy were gay in the older series vs the Adult Cartoon Party when they actually... well... it's in the first episode, thankfully hidden even with a TV MA rating.