I make an arse out of myself at least twice a month from butchering the pronunciation of a word. There are only two things you can do when you have no idea how to say something -- either quietly whisper but quickly gloss over the word so no one hears you, or say it with such complete confidence that you confuse the hell out of people who really do know how it's pronounced.
And if those people dare to bring up the proper pronunciation of the word with you, just agree with them saying you thought it was that way too until you heard David Attenborough or some other plum-voiced person pronounce it your (wrong) way. It's foolproof! What? There's a third option to actually figure out how the word is pronounced? That's lunacy!
The very interesting and very wrinkled brain of John Green of Mental Floss came up with a list of 79 commonly mispronounced English words, albeit, in the US. So while some of these pronunciations don't apply to us on these fair shores, some of these will still apply to you and I. I mean, really -- everyone should know how to say: colonel, epitome, meme and so on. Pwned and GIF get some clarification too (it's powned and hard-g GIF!). [Mental Floss]