The rules of punctuation seem arbitrary. How can they not, when an apostrophe looks like nothing in this world so much as a comma that can’t keep its feet on the ground? Or when, by simply placing next to that wafting comma its twin, one creates (of all things) a quotation mark? – Richard Lederer and John Shore, Comma Sense: A Fun-damental Guide to Punctuation

The great logical, or grammatical, framework of language, (for grammar is the logic of speech, even as logic is the grammar of reason,) he would possess, he knew not how… – Richard Chenevix Trench, “On the Study of Words,” lecture to the pupils of the D

I always put the apostrophe in “ain’t” to make certain I’m using proper improper English. – Author unknown