One of my favorite Simpsons lines of all time: (Krusty mimicks doing a line of cocaine, then notices Bart and Lisa are watching) "Uhhh, you know? Smelling flowers? (Quietly, to himself) Such expensive flowers, filled with remorse…
Another marajuana one: “Stoner’s Pot Palace’, that’s false advertising man.”
As far as pot jokes go, there’s also Lisa’s remark at Hullabalooza that something “smells like Otto’s jacket.” And when Homer is toking up in the medical marijuana episode, she notes that it "smells like the art teachers’ lounge. 
Isn’t there an episode where Bart or Lisa dons a virtual reality helmet and sees a virtual pillaging mob and chats with Ghengis Khan? (Probably one of those flash-forwards.)
“Oh, hello there. I’m Genghis Khan, and for the next hour you’ll see what I see, hear what I hear, and kill who I kill!” I think that was a daydream of what the school could do with the oil money in the first “Who Shot Mr. Burns” episode?
Another drug joke: Ralph gets a box addressed to Otto from the post office’s Undeliverable Mail section. The guard dogs start barking and straining to get to it, and he exclaims, “I got dog food!”
More drug humour: Marge, pumped up on steroids, stops the Springfield Elementary schoolbus by lifting the back wheels off the ground. Otto, suspecting this unlikely turn of events is a hallucination, asks himself “Man, what am I smoking? [looks at doobie in his hand] Oh yeah, pot.”
A twofer.
Hmmm…
Has Marge ever razed a whorehouse with a bulldozer?
No, the bulldozer did it by itself.
Have they done…
The Seymour Skinner porn connection? (C’mon. “See More Skin?”)
Unwed working mothers?
Bigamy?
Teachers having inappropiate relations with students?
M. Night Shymalan parodies/references?
A whorehouse?
Street gangs?
Real-life rich Bill Gates/Donald Trump, etc in business with C. Montgomery Burns?
Registered sex offenders?
Marge’s friend, the mother of Bart’s first real crush used to be married. Does that count?
[QUOTE=Askia]
Have they done…
His mother once commented “I hear what you do in there (your bedroom) at night.” Who knows?
Yes. Homer (with Flanders) got trashed and married a woman in Vegas a few seasons ago.
Mrs. K: “Bart, you’re the closest thing to a man in my life . . . and that is so depressing, I think I’m gonna cry.” Okay, the first half works.
Bart wrote “I see dead people” on the chalkboard before one episode.
Yes, there was a whole episode about it.
Does the episode where Bart forms an army and attacks Nelson with water balloons count? Or Homer’s vigilante group? Or the one where Grampa and his old friends race a car against another bunch of old men?
Hasn’t happened, but Bill Gates (not voiced by himself) and his thugs did bust up Homer’s internet venture, CompuGlobalHyperMegaNet. “I didn’t get rich by writing a lot of checks. ‘Buy him out’, boys!”
There’s at least one whole season left. 
“Are they talking about the bordello?”
“No! So keep your mouth shut!”
Well, there was one ep where we saw the line to register as a sex offender…and I don’t remember which one it was.
Moe: Ah geez, there’s always a line!
[QUOTE=Marley23]
His mother once commented “I hear what you do in there (your bedroom) at night.” Who knows?[/QOUTE]
But didn’t he say he wasn’t looking at porn? So his mother called him a wuss.
There was also the motorcycle gang episode “Hell’s Satan’s” and the snack food franchise episode where the mob and yakuza had a gang war on the Simpson’s front lawn. Not exactly street gangs, but gangs in general.
Lovejoy: I know one of you is responsible for [changing the hymns]. So repeat after me: If I withhold the truth, may I go straight to Hell where I will eat nought but burning hot coals and drink naught but burning hot cola –
[all the kids recite in unison]
Ralph: [scared] …where fiery demons will punch me in the back,
Bart: [bored] …where my soul will be chopped into confetti and be strewn upon a parade of murderers and single mothers,
Milhouse: …where my tongue will be torn out by ravenous birds. [a crow outside looks right at him an squawks] Bart did it! That Bart right there!
Bart: [angry] Milhouse!
Lovejoy: Milhouse, you did the right thing. Bart, come with me for punishment. [goes back for Milhouse] You too, snitchy.
Emphasis added.
The episode where Homer becomes head of Springfield Sanitation. He goes into a city office and says he wants to sign up to run in the next election, only to be told he’s in the office for registering sex offenders. Moe walks in and says “Geez… there’s always a line”.
Son of a BITCH. You guys are good! I thought I had you (and the show) at five of my suggestions, at least. You got it narrowed down to two!
I see I have to get more creative.
TRANSPORTATION
Zeppelins.
Monorails.
Segways.
Submarines.
Tandem bicycles.
POP CULTURE / TECHNOLOGICAL REFERENCES
Iraqi WMDs
The NBA
Cyberstalking
The Tour De France
Cicadas
Global Positioning Devices
The Atkins Diet
10 points apiece to every creditable reference. GO, my research monkeys!
Barney crashes the Duff blimp, causing Kent Brokman to comment “Oh! The humanity!” Also, Bart’s checkbook is a flip series,showing the crash of the Hindenberg.
Is there a chance the track could bend?
Not on your life, my Hindu friend!
It’s my first day!
Selma once showed a photograph of herself and Patty riding one. Selma wasn’t sure which twin in the photo was her.
The episode where the reactor’s about to meltdown, and Homer randomly punches a button and saves the day featured an NBA basketball star as the guest voice for that episode.