I prefer, at nighttime, the McDonalds at Karlsplatz/Stachus or the new one in the central train stations (beware though, both are notorious for a lack of power outlets!), and if you're into bagels/muffins, head to tram 27 Schellingstraße, there is the Fresh Bagels & Muffins. Great bagels, dude.
If you're into cats, head to cat cafe Katzentempel at Türkenstr 29, it's in walking distance of FBuM.
Oh, and if you mean "getting wasted" with "getting stuff done", head either to Ostbahnhof's Kultfabrik area (just follow the drunks) or to the club areas at tram station Am Lokschuppen. The club "Nachtgalerie" is famous for cheap drinks, but well, it's mainstream music.
Have a nice stay!
