The Ethiopian calendar has 12 months of 30 days plus a thirteenth month of five or six days (leap year every four years).
Their national travel motto is "Thirteen months of sunshine".
They also start their clock at (our) 6am which can be a bit confusing when making appointments to meet people (our 10am is their 4am).
They also missed the Gregorian calendar correction so it's now 2006!
From Wikipedia:
Like the Coptic calendar, the Ethiopic or Ge'ez calendar has twelve months of exactly 30 days each plus five or six pagome days, which comprise a thirteenth month. The Ethiopian months begin on the same days as those of the Coptic calendar, but their names are in Ge'ez. The sixth epagomenal day is added every four years without exception on August 29 of the Julian calendar, six months before the Julian leap day. Thus the first day of the Ethiopian year, 1 Mäskäräm, for years between 1901 and 2099 (inclusive), is usually September 11 (Gregorian). It, however, falls on September 12 in years before the Gregorian leap year.
The current year according to the Ethiopian calendar is 2006, which began on September 11, 2013 AD of the Gregorian calendar.