A portmanteau comprised from the expressions
Captain Obvious} and [King of the Assclowns, aka Donald Trump. It is a clever play-on-
words and ideas because it demotes Trump from his
real-world title of President and Commander-in-Chief, and his wannabe title of King of the World, to the rank of a mere captain, and that being inferred as more-stupid than the low-IQ Captain Obvious.