Carnaval is a colorful tradition during February and March in Abancay [1] and apparently includes a contest in which young men spar with whips.
The Yawar Fiesta is celebrated in Antabamba on October 8. Abancay Day, a large town party, is November 3.
The main strip in Abancay [1] is first called Arenas and then becomes Arequipa, and it’s where all the discos, bus stations, cheap restaurants, and hostels are. A popular evening hangout is the Parque Micaela Bastidas, on the second block of Arenas.
The pub to hang out in is Garabato (Arenas 164, 7 p.m.–1 a.m. daily), with furry benches, full bar, and nice atmosphere. It has a sister pub in Cusco [2].
There are several other pubs in this vicinity. The best disco is the nearby Choza Inn (Arequipa, block 3, weekends only).
Links:
[1] http://www.moon.com/destinations/peru/central-highlands/abancay
[2] http://www.moon.com/destinations/peru/cusco