Usually prefixed with "I feel like a..."
A phrase meaning to literally not fit in - to be out of place, or wrong for your environment.
I often feel like the proverbial square peg as I have chosen to work somewhere which really is not me. Smack bang in the middle of Corporate World, where creativity and ideas are less important than playing the game and towing the line. (Like many people this may be why I spend so much time on E2!)
Sometimes the feeling of my squareness being quite literally sanded down and forcibly rounded is palpable and I feel like my whole being is being shoved violently into this wrong-shaped hole while I yell, No No, let me stay square!
The thing about this saying is that pegs are round, as are holes. So by definition being the square peg makes you the odd one. But I quite like that.