When someone's moniker or nickname follows the form of a first name of whatever form and then has a surname of the form Mc and then some descriptive adjective (which may be suffixed with "pants"). Often used as a cheap and easy way to make a name into a pun. Just stick a Mc or Mac onto the front and everyone will know that it's a surname. Of course you can do this with any other common onomastic prefix or suffix: e.g., Paddy O'Adjective, Hassan Ibn Description, Baron Von Word, Verbal Verbson etc. A common feature of Buffy-Speak. Compare Awesome McCoolname and Fail O'Suckyname.