Siege of Mafeking was relieved. After 217 days of attack from the Boers the British re-enforcements arrived and, when the news got back to Britain, there were wild celebrations. The Boer War had been going badly and any good news was a good excuse to party riotously, or, to use the contemporary term, to maffick.
Mafeking is not, of course, a participle. In fact, it's from the Tswana meaning place of rocks. But that didn't stop people treating it as though it were one. So just as sideling became sidle, so Mafeking became maffick, meaning to celebrate uproariously.
Incidentally, the commander of the British forces at Mafeking was one Robert Baden-Powell, who then founded the scout movement, and wrote a book called Scouting For Boys, which is, apparently, the fourth best selling book of the twentieth century.
Anyway, the weekend is here, so have a good maffick.