The mythical university where all wise potheads once went to learn all of the seemingly random stuff they know about bud. This is a reference to the movie Half Baked, in which Thurgood says the line "What, did you go to weed college?" after another character says a sentence to him in pure weed jargon.

The basic curriculum consists of:
PIPE 107: using bongs and steamrollers without coughing, and how to clear properly.
WEED 121: telling quality schwag from the cheap mexi stuff.
ROLL 115: rolling the perfect joint, from breaking up to tapering down.
TALK 188: definitions of basic words like ganja, shake, space cake, dugout, and so forth.
STSH 268: where best to put your dope so that no one (possibly including yourself) will ever find it.
DEAL 214: buying from dealers without getting burnt. Postal scale required.
WEED 250: learning the weight, size, and look of different amounts of grass in bags and bricks.
MNCH 310: the zen-like art of not needing to eat after a smoking session.
ROLL 319: rolling blunts, phattys, spliffs, and other advanced rolling technique.

There are more advanced upper level electives, too:
WEED 412: the difference between indica and sativa.
PIPE 510: turning any hollow object into a pipe or bong.
WEED 430: different types of kind bud, from Purple Haze to Northern Lights.
TALK 560: speaking eloquently about marijuana, even while under its influence.
STSH 672: where, how, and when to hide many pounds of grass.
TALK 420: the etymology and story of the term 420.
DEAL 614: dealing without getting arrested or burnt.
GROW 663: turning an empty bedroom into a large source of income.
etc.

Suffice it to say, if you know most or all of these things, you have probably been to weed college. The fact that you don't remember going can be considered additional proof ;-)