These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Tom Lehrer
Crosses the Line Twice: "We'll murder them all amid laughter and merriment, except for the few we take home to experiment!"
Another pair of examples is The Old Dope Peddler, which was so over the top when it was written that people nearly died of laughter, but when performed to modern audiences, the laughter just . . . dies away by the end because it's too topical, and The Masochism Tango, which is so over the top it still crosses the line in the day and age of the Obligatory Bondage Song.
And "We Will All Go Together When We Go", which was about a nuclear holocaust.
"Just sing out a Te Deum/When you see that ICBM/And the party will be 'come as you are'!"
At least half his songs qualify for this trope - and they don't cross the line twice so much as dance back & forth over the line, to the sound of a catchy little piano ditty.
Special mention must surely go to "I Got it from Agnes", which opens with the simple premise that an STD is working its way around his group of friends and they're happy with this. Then, as it lists who got it from whom, you notice around the second verse that some of his friends are clearly gay - a little controversial for its day, but nothing major. Then it mentions Pierre, who got it from Francois and Jack. And Edith who got it from her father. And Daniel, whose spaniel has it now. And then it reveals that their dentist even got it and they're stillwonderinghow.
This one manages to use this trope while still Getting Crap Past the Radar by never actually stating what "it" is that everyone is getting from one another. The listener's mind does all the work.
Dammit, I've had "2,4,6,8, time to transubstantiate" from The Vatican Rag in my head for a week now.
Richard Dawkins has claimed to have had "Masochism Tango" stuck in his head.
Harsher in Hindsight: Possibly I Got It From Agnes, written between the introduction of antibiotics and the rise of AIDS. For a few decades 'V.D.' was unpleasant but not that scary.
Hilarious in Hindsight: His 1960s song "George Murphy," about a senator with a former showbiz career, gets a cheap laugh from the less-than-impressive career of another politician with similar background...Ronald Reagan.
But plagiarize, plagiarize, plagiarize! note ...only be sure always to call it, please... "research."
Seinfeld Is Unfunny: By 1960s standards, his work was some of the funniest, most obscene material written. Today, it's fairly tame.
Squick: It is a considerable credit to his songwriting talents that even after nearly half a century and all the moral decay that entails, the Black Comedy of some of his lyrics can still turn a few heads.