Aliens Speaking English: "This book is designed to provide you with the next best thing to our actual presence: a comprehensive history of our species, conveniently written in the universal language—American English."
Anal Probing: Mentioned in the Foreword as one thing humans who believe aliens have already visited Earth think extra-terrestrials came here to perform. It then refers to the anus as "the orifice least likely to yield useful pedagogical results." Mykonos, Greece is described as the one place that would have been the most receptive to Anal Probing.
For the titles of articles, at least. 95% of the book is read by Jon Stewart.
Church of Happyology: Notably averted. The book takes several potshots at the Church of Scientology explicitly and by name. One quote about the book attributed to L. Ron Hubbard on the cover reads,
"A shameless scam that passes off meaningless drivel as timeless wisdom in a brazen attempt to wrest money from the vulnerable and ill-informed. Two thumbs up!"
Confess in Confidence: Subverted. There is a transcript of a confession where the person confesses to: speeding, a hit-and-run, hitting a cop in the hit-and-run, robbing a bank, and murdering people in the robbery. This causes the priest lots of discomfort. It seems completely played straight, until you realize it was transcribed. This is lampshaded, saying the transcriptions were for 'insurance purposes.'
Fun with Acronyms: Every chapter ends with an FAQ (Future Alien Questions) Section to answer the most likely questions aliens may have about us and Earth after reading about the subjects covered therein.
George Clooney: The book says that if the aliens that find our dna can only replicate one thing, it has to be, "that mischievous twinkle found in George Clooney's eyes"
Humans Are Bastards: In the Table of Contents, "Chapter 3: Man" is summarized as, "An introduction to the solar system's original 'bad boys.'"
Humans Are Morons: Anything that doesn't make us look crazy or evil makes us look like complete idiots. For instance, "not masturbating on a mass-transit system" is the example used to explain the "harsh, at times maddeningly frustrating trade-offs" that served as the basis for a social contract.
Another example comes at the end of the FAQ Section on Chapter 2: Life, revolving around the author refusing to explain to aliens what creationism is, despite "billions of people" believing in it as the origin of life up until the end.
Q. Come on.
A. Look, if you're so damn curious, check into a hotel room, open the bedside table and start reading.
Q. Hold on a moment. [Pause]
A. We know.
Q. Six days? Six days?!?
A. [Covers eyes, shakes head]
I Want My Jetpack: An in-universe example. In one of the FAQ Sections at the end of each chapter, the aliens ask (paraphrased) "what is the invention or scientific advancement that you most regret not accomplishing?" The answer: Jetpack, jetpack, jetpack, and jetpack would be 1 through 4, 5 would probably be the cure for cancer, then jetpack.
As our larynxes descended, we were able to make sounds with our mouths in new and far more expressive ways. Verbal language soon overtook physical gesturing as the primary means of communication for all human beings except Italians.
Nothing Personal: The "Just business" version of the stock phrase is mentioned and explained as just another absurdity of human nature (i.e. that trade is exempt from normal moral codes of conduct).
You may not shoot members of the Red Cross (not even a little), nor prevent them from inspecting your prisons, nor touch their property, nor leave live hand grenades in their medical kits, nor get fresh with their nurses, nor fling dead rats at them for a laugh, nor...look, just stay the fuck away from the Red Cross, OK? Who do you think wrote this thing?
Uranus Is Showing: Uranus is described as being "the funniest planet by far," although any aliens would "have to spend about ten years learning idiomatic English to learn why." Lake Titicaca is also identified as "The 'Uranus' of Lakes."
What Is This Thing You Call Love?: "Love", as the book explains, was just a chemical reaction in the brain that caused two individuals to enjoy each other's company to a higher degree than normal, with the side-benefit of often resulting in a prolonged union and children, to further continue the species. Completely unremarkable, and not considered that big a deal by humanity at large.