Rudy's Pub
Until recent years, it was the Blue Marlin weekly party on Mondays that took the honours on the island. Rudy's has now definitely assumed that mantle with its Friday night bashes. Gets very messy indeed. On non-party nights, still often gets a crowd.
Sama Sama
Live reggae music every night. Despite feeling like it is stuck in a timewarp, this place really pumps and is a lot of fun.
Horizontal
Probably the only place in the Gilis that wouldn't look out of place in Seminyak, this stylish outdoor bar offers fancy drinks, funky furniture and DJs spinning the night away. Also has rooms for rent.
Ocean Dua
The nearest thing the islands have to a specialist sports bar, with large screen TVs showing round the clock EPL and other sports.
There are regular party nights on Gili Trawangan - the various bars take it in turn to host the late night gig up to 4AM, to ensure that everyone gets together in one place rather than being spread around. The island is small and it is easy to find everything; just ask around for where the party is going to be on any given night.
Be very careful with locally produced booze, especially arak. It can contain methanol and has caused many cases of serious injury and even death among tourists and locals alike.