So I'm in my business calculus course that I just finished up, and we're taking notes while the professor is lecturing (25 or so students in the course) , and I'm trying to sketch a graph, but make a mistake, and I have to start over again. I mutter quietly to myself "You fucking idiot, learn how to fucking draw." A couple of seconds later, the guy sitting next to me starts laughing, and I look at him and whisper, "I said that really loud didn't I?", and he replies "Yea". A few seconds later, the entire class including the professor start bursting out laughing. The professor was really laid back so he didn't care, and I started laughing along at my faux pas.
Sigh I really really need to learn to keep quiet.