Just poking around the 'nets and I tripped over something I'd like to share. I've been waaaaay guilty of this myself, so I'm not posting it to shame anyone, just for the lulz (as the kids say). (Disclaimer: stolen wholesale from Wikipedia. No original content beyond this point. Formatting automagically screwed up by cut-n-paste. See the original in Wikipedia if you want to see the footnotes.)

Skitt's Law:

A corollary of Muphry's law, variously expressed as, "Any post correcting an error in another post will contain at least one error itself," or, "The likelihood of an error in a post is directly proportional to the embarrassment it will cause the poster."

Muphry's Law:

Muphry's law is an adage that states that "if you write anything criticizing editing or proofreading, there will be a fault of some kind in what you have written." The name is a deliberate misspelling of "Murphy's law."

John Bangsund of the Society of Editors (Victoria) in Australia identified Muphry's law as "the editorial application of the better-known Murphy's law"[5][6] and set it down in 1992 in the Society of Editors Newsletter.[7]
The law, as set out by Bangsund, states that:
(a) if you write anything criticizing editing or proofreading, there will be a fault of some kind in what you have written;
(b) if an author thanks you in a book for your editing or proofreading, there will be mistakes in the book;
(c) the stronger the sentiment expressed in (a) and (b), the greater the fault;
(d) any book devoted to editing or style will be internally inconsistent.[7]
It goes on to say:
Muphry's Law also dictates that, if a mistake is as plain as the nose on your face, everyone can see it but you. Your readers will always notice errors in a title, in headings, in the first paragraph of anything, and in the top lines of a new page. These are the very places where authors, editors and proofreaders are most likely to make mistakes.[5]