GUFF (the Get Up-and-over Fan Fund, or the Going Under Fan Fund, depending on the direction of travel) was dreamed up by Chris Priest in 1977 to complete the triangle of fan funds and to bring an Australian fan to Britain for the 1979 Worldcon. Without the tiresome business of actually having a free trip anywhere, Dave Langford (UK) and Leigh Edmonds (in Australia) were the first administrators, and John Foyster was the first winner, and it seemed rather a nice idea to continue. The name DUFF being already taken, Chris imagined GUFF as standing for the Get Up-and-over Fan Fund, which didn't sound so brilliant when time came to do a southward trip, but as Don Marquis (who never stood for the fund either) so aptly put it, you can't have everything [This description mostly provided by Dave Langford with the admonition that it needs to be marked "Copyright (c) Astral Leauge 1979 do not impinge copyright or the Leauge will take MEASURES.")]
The fund continues to send fans between Australasia (mainly Australia and New Zealand) and the U.K. or Europe. Although trips alternate the the direction of travel, the intervals between trips vary.
GUFF is patterned after TAFF and DUFF, with fund winners being co-administrators of the fund until the next winner from their respective continent returns from a trip. GUFF winners, like winners of other fan funds, are expected to publish a trip report.
More details about GUFF, including a full list of winners with details and contact information for current administrators, are available from the GUFF page at Fanac.org.