Probably the best place for big cheesy old-skool studenty club nights: 90s, rock, r'n'b, etc. Check their website for schedule.
Getting there: From the hostel, take the U6 U-Bahn line from Westbahnhof (direction 'Siebenhirten') to Längenfeldgasse and walk 5 minutes from there.
Getting back: The U-Bahn runs back to Westbahnhof through the night Fri & Sat. From Sun - Thurs, the last train at night is around 00:30; after that you'll need to either uber / taxi it or walk (about 25 mins).