Well, it very much depends on where you are.
My usual source of drink is of course down the pub, and then I am very much a regular cider drinker. However I wish to make it absolutely clear that Strongbow does NOT count as cider, as although cheap it just doesn't taste good. Ideally I'd have a local brand (as I am living in Somerset, UK they are pretty common!), or have a bit of the old Scrumpy Jack. Now that has a kick!!
When drinking in with a few mates nothing beats whisky, and of course top of the list is the mighty Jack Daniels. However Southern Comfort isn't too shabby, and is nice and cheap (obviously essential for any self respecting student), and if whisky is unavailable then a bit of black rum hits the spot!
Finally, when eating a meal then wine is the only way to go. A good white can be bought for less than a fiver, and a bottle can have you merry for the rest of the night. Red is a bit more difficult, and the cheap stuff tends to be too much like vinegar, but when the parents are paying a good red is hard to beat!
Finally, to anyone who said Carling, you clearly have very poor taste. Although traditionally the cheapest pint available, it is horribly watery and leaves your stomach in a right mess the next morning. If you are going to drink beer then nothing beats a bit of San Miguel, or any of the continental European beers (I once had a great one in Vienna, though I can't recall the name)