A note about the webcomic, and then some notes about the idiom everybody and his brother.
From the Wikipedia entry:
Cyanide and Happiness is a webcomic hosted on Explosm.net and written by four authors [Kris Wilson, Rob DenBleyker, Matt Melvin, Dave McElfatrick] with occasional contributions from guests. It was founded on 9 December 2004 and has hosted almost daily comics since 26 January 2005. It appears frequently on social networking sites (such as Myspace and LiveJournal), web forums, and blogs as it openly allows and encourages fans to hotlink images, a behavior that many webcomics frown upon as “leeching”. The comic’s authors attribute the comic’s success to its often controversial nature.
… The style of Cyanide and Happiness is best described as dark, cynical, often offensive, and exceedingly irreverent. Frequent topics of humor include disabilities, terrorism, rape, cancer, murder, necrophilia, pedophilia, sexual deviancy, sexually transmitted diseases, self-harm, and vehicular manslaughter. These topics are usually introduced in an unexpected or shocking way …
Now the idiom everybody and his brother: this is a hyped-up expansion of everybody, and like a great many idioms it allows for a certain amount of variation in its parts.
The Free Dictionary has material on the idiom from the McGraw-Hill Dictionary of American Idioms and Phrasal Verbs (2002), where it’s listed as everybody and his brother, with the variant everybody and his uncle, the gloss ‘everybody; lots of people’, and the example
The state fair was packed. Everybody and his brother was there.
(The example is important. Note the singular verb agreement — just like everybody, while lots of people would call for plural agreement. I’ll take up the agreement issue in a while.)
Wiktionary has the variant everybody and his cousin ‘everybody; a huge crowd; too many people’, plus the synonyms
everybody and his grandma (US), the whole world and his dog (UK)
It also has everybody and their brother ‘a large number of people; most people’, with the synonyms
everyone and their brother, everybody and their dog, the world and his wife [not marked as UK, but it probably should be]
(Crowd-compiling of dictionaries tends to be a haphazard thing.)
Everybody and their brother — with generic singular their (anaphoric to everybody) rather than generic his — is very common indeed, and their stands as an alternative to his in variants with nouns other than brother (especially dog), as in these variants from the WordReference Forum: everybody and his kid sister and everybody and his wife (in which the denotation of everybody is clearly limited to males).
Now, the agreement question. This comes up on language forums on the net every so often; dispute regularly ensues. On Yahoo! Answers, one respondent gave the very reasonable answer:
It could be singular because everybody requires a singular verb. It could also be plural because when two or more subjects are connected by “and” it requires a plural verb. [try not to worry about the denotation of that last it]
but she was soundly voted down by the voters on the question, who opted for plural verb agreement, on formal grounds.
But in raw ghits, writers on the net go the other way: 414,000 everybody and his brother was, 76,100 everybody and his brother were, for a 5.4-to-1 ratio. See the idiom-dictionary example above. There’s an even stronger preference for is over are: ratio of 7.3 — despite the cartoon that started this whole discussion, where their is used in a clearly male context.
This is yet another case where different principles, each having some justification, conflict, and actual practice sometimes goes one way, sometimes the other. Either choice is acceptable (and reasonable) — there’s no One Right Way — though there’s often a considerable preference for one choice in practice. But when people try to reason their way through things as a matter of principle, they’re sometimes more likely to make the other choice.
(Note the many cases, much studied, where conjuncts joined by and take singular verb agreement (obligatorily or optionally), for instance when the conjuncts denote the same entity — The producer and director is famous for her extraordinary shows — or when the referents together constitute a conceptual unit, as in Bacon and eggs is not really a healthy breakfast. In the his brother idiom family, we have another case: everybody and his brother has the same denotation as everybody, though differing from it stylistically.)
As for everybody and his dick, it seems to be novel (though dick is close to dog phonologically, so it’s a short hop), and it’s notable in treating a man and his penis as separate sentient beings (though penis words can be used metonymically to stand for a man, just as ass can be used to stand for a whole person). Of course, conceptualizing the penis as a separate entity (“with a mind of its own”) is a standard trope in our culture (and, probably, many others). Still, having your penis post on a social network is a bit startling.
(And then there’s the rich territory of putting someone’s penis in your circles. Or vice versa, meaning putting your penis in someone’s circles.)