(Adj.) Someone who exaggerates the truth. A person whom most often then not, always has a story to tell in relation to the conversation, most often the story is made up or a gross exaggeration of the truth.
"Bob, did you see that J.F.K. Documentary?" "My brother's roomates uncles, fathers, sister, friends, aunt is best friends with J.F.K." "Damn, Bob you are such a cacker!"
Someone who believes they always have the answers, a know-it-all. Usually used to insult that person when they make a stupid insight or just repeat what has already been said. Sherlock being a reference to the literary detective sherlock Holmes.
"We should fix this tire."
"Well, if I were you I'd fix the tire."
"NO SHIT SHERLOCK!"