Whenever I'm writing a script or a novel chapter I'm always in and out of Thesaurus.com and Wiktionary, trying to make sure that all the words and phrases I'm using mean what I think they mean and are spelled the way I think they're spelled.
It might sound paranoid, but human language is organic, after all: it's easier than you'd think to get an idea in your head about how something should be said that isn't quite right, and then you end up looking like an idiot to people who know better. :]
So I thought it might be cool to share some of these common phrases and possibly save somebody's skin, or make them re-evaluate the way they've spoken all their life; whichever. ^^ It's one of those things you may never find out about unless somebody tells you.
Here are some of the ones I know:
-'FOR ALL INTENTS AND PURPOSES', not 'for all intensive purposes'
-'ET CETERA', not 'etcetera' or 'ecksetera'
-E.G. means "for example", while I.E. means "in essence", "basically"
-'NOWADAYS', not 'now in days'
-'EFFECT' is a noun ("cause and effect") while 'AFFECT' is a verb (people are "affected")...in general usage, anyway. ;]
-People are 'SUPPOSED TO BE' things, not 'opposed to be' things.
-'MACARONS' and 'MACAROONS' are both sweet treats, but they're not the same thing!
-'VOILA', not 'walla'
-Apparently, 'alot' isn't a thing. It's supposed to be two separate words, 'A LOT'
-'ESPECIALLY', not 'exspecially' or 'ecspecially'
-'PARFAIT', not 'parfay'
-'BLOND' and 'BLONDE' are just the male and female French versions of the same word. I use them accordingly in English, but I don't think most non-French speakers would care...except when using the word to refer to a female, as in "brunettes, redheads, and blondes"
-'JUDGMENT' and 'JUDGEMENT' are both acceptable forms, but the former is more common
-'THEM'S THE BREAKS', not 'them's the brakes'
-'DIRE STRAITS', not 'dire straights'
-'MISCHIEVOUS', not 'mischevious'