Even as a kid, I knew something was dirty about Krusty's joke setup, I just didn't get what it was: "This guy walks into a bar and takes out a tiny piano and a twelve-inch pianist. Oh no, wait! I can't tell that one!" Dear 9-year-old me, welcome to Dick-jokesville. Population, you.
Even a prepubescent ignoramus could pick up on "the real deal" with Mr. Smithers, but although I got that he was latently gay, I missed a lot of the jokes that went along with it. Probably the most notorious example came in the third Treehouse of Horror episode when Mr. Burns asked for Smithers' opinion about taking Marge along in a ship full of sailors. Smithers' answer: "I think women and sea-men don't mix." Oh! That. Got it.
As a kid, I did a pretty good impression of Ned Flanders, which basically entailed throwing "diddly" onto the end of words. But when watching "Bart The Lover," I did not understand why my parents chuckled at one particular line which was virtually diddly-free. Now I get that Flanders accident-diddly-ally let out a few innuend-doodly-endos: "All of us pull a few boners now and then, go off half-cocked, make asses of ourselves. I don't want to be hard on you..." Oh, 9-year-old me, you don't fully appreciate the simple pleasures of a good boner joke. But you will!
I was a couple of years older than Bart when "Homer's Phobia" aired, but both of us were too naive to pick up on his wonderful double entendre when he tells Homer that his Hawaiian shirt "came out of the closet." I honestly thought the punchline was the idea that Bart found a Hawaiian shirt in his closet. Why I thought that was funny, I don't know.
(This is technically a 'sexual-orientation' joke more than an actually-sexual joke, but still, it wasn't exactly in my joke-getting wheelhouse back in 1997)
Homer and Marge have a pretty active sex life, as is made clear by their frequent references to "snuggling." (Snuggling totally means doin' it, you guys.) In hindsight, these peeks into their bedroom antics were pretty unsettling, given that Homer and Marge essentially raised me as my TV parents, but one line that sticks out as being particularly sexual appears in the episode "Whacking Day" when they discuss the fine art of snake-whacking. Homer asks seductively, "Should I whack slow or fast?" And Marge responds, "Slow...then fast." I understood that they were being frisky, but it would've melted my tiny brain to imagine Homer and Marge "whacking" anything. It's bad enough that when the busty Ms. Springfield says, "Gentlemen, start your whacking!" it made me feel all weird in the pants.
It's sort of embarrassing for Homer that he first learned about sex from a zookeeper, but it's even more embarrassing for me that I first learned about sex from Homer's story about learning about sex from a zookeeper. What's hilarious about this scene is that after Homer says, "Zookeeper! Zookeeper! Those monkeys are killing each other!" The zookeeper whispers into Homer's ear and if you listen closely, you can hear him saying, "They're having sex." The look of sudden understanding on Homer's face is priceless. It's likely the same one I made while watching that scene for the first time.
As mentioned, lots of kinky stuff went down in the Simpsons' master bedroom. Possibly the kinkiest of them all was when Marge asked Homer to wear the Mr. Plow jacket to bed. Now, there are two ways to interpret that. One fairly harmless way in which I saw it as a kid: Marge enjoys the sight of her husband in uniform. Not too weird. The other is that Homer is wearing a jacket that says MR. PLOW on it to bed where he will do some...uh, well. Take that as you will. Bet you'll never sing the Mr. Plow song the same again.
The ending scene of "Life in the Fast Lane" didn't make a ton of sense to me for a bunch of reasons. For starters, it's virtually identical to one from "An Officer and A Gentleman," a movie which wasn't as popular with me in 1992 as "Home Alone 2: Lost in New York." So that went over my head. Then, there is the closing line. The joke that I suddenly got immediately after my first sexual encounter: "I'm going to the backseat of my car with the woman I love... and I won't be back for ten minutes!"
When I was a kid, "condom" was one of those words that I'd heard, I understood that it was a sex thing, but I wasn't really sure exactly what it was. Of course, now I'm an adult and I've used nearly a dozen condoms in my lifetime. Not to brag! So now I totally get how weird it was when Grampa Simpson picks up a condom wrapper and says, "'Laaaaay-tex connn-dome.' Boy, I'd like to live in one of those!" (In a bonus creepy sexual reference by Grampa, in another episode, he mentions his plans to sell sex tonic in the towns of Frigid Falls, Mount Seldom, and Lake Flaccid. That's some good boner punnery right there.)
I went to a Catholic school where sexual education was not taught, so "Fuzzy Bunny's Guide To You Know What" was the first and only sex ed video I ever saw, even if it was fictional. It answered a lot of questions about why I had terrible acne and fur where there was no fur before. But clearly, Mrs. Krabappel watched with a much more jaded understanding than I did. Her reaction: "She's faking it." Sadly, I now understand what she meant.