noun, pronounced "Spee-Oh"
acronym for Self Proclaimed Expert On Everything
The annoying know-it-all in everyone's social circle, or quasi-member thereof, who always insists on one-upping the person controlling a current conversation with useless factoids or name-dropping to make himself appear more knowledgable or superior to the audience in question. Considers himself (herself) the perfect candidate for "Jeopardy"
Did you hear how many times he interrupted her description of her trip to New York to correct her and brag about his trip to Boston. Dude, he is such a SPEOE
descriptive noun: The butthole who always insists on having the last word, regardless of the validity of his arguement. Will insist the earth is flat, even as he sails over the horizon.
He's such an Iknowbutt! I told him he'd electrocute himself with the hairdryer in the bathtub, but he just said, "I know, but if I am really careful, I can just paralyze myself and get a big settlement from the hairdryer company."