Literally "Talking Crap." Referring to someone making up a whole lot of lies, or telling a really tall story that can't possibly be true, usually to get out of trouble, or to simply sound like a smart aleck but failing miserably when the listener to the smart aleckcomment actually knows what the deal is anyway.
From the Latin words "Copro", meaning faeces, and "articulation", meaning speech.
"You have given me a very elaborate excuse as to why you were late to work, and I don't believe a word of it. However, I do believe that you are engaging in a highly imaginative form of coproarticulation."