Depends on the situation.
If I care about taste, I'll make (or buy) a Tom Collins or a Turkey & 7, maybe a Red Bull & Vodka.
If I'm just trying to get drunk, it's whatever's cheap if I'm at a bar, or a couple of Steel Reserve 211 Black Labels if I'm not ... 8%BV malt liquor ... $1.59 for a 24oz can.
If I want a lot of beer for cheap I'll buy a Heineken mini-keg for $20.00.
If I want good dark beer I'll scour the city for Spaten Optimator.
If I'm feeling vodka it's Svedka or Stoli. Rum is Captain Morgan, and always mixed with Coke. If I'm in Lafayette, it's the pitchers of Amber Bock we get for $5, and if I'm in Atlanta it's let's mix Everclear with anything, hop on the subway, and try to remember where we went the next morning.