Lurgi, the lurgi or the dreaded lurgi (also sometimes spelt lurgy) rhymes with Fergie and is a lovely informal BrE word with comedic (and possibly dialectal) origins that can now refer to an annoying (but not serious) illness that hangs around and makes one feel miserable. World Wide Words does a lovely job of recounting its history. Wiktionary has more on its meanings. In addition to meaning 'flu-like symptoms' it has a playground use that is somewhat equivalent to AmE cooties, which you can learn more about here or in the following video:
But that's all from me now, 'cause I've got the lurgi.