1. (noun) - marijuana. There are already a million definitions here, but it is worth mentioning that pot is considered a bit old-fashioned these days. Your old man would call it pot or grass. More commonly called weed, dope, hash or shit by most.
2. (noun) a toilet, and really only used in the phrase in the example below, meaning to hurry up and do something or bugger off, as long as you get out of the way.
3. (noun) the standard sized beer glass used in pubs in the state of Victoria. Holds 10oz or 285mL.
4. (noun) a cylinder in a car engine, usually preceded by the number.
5. (verb) to score a goal in football. Snag is another. Probably stolen from snooker.

1. Are you kids smoking pot in there???
2. Either shit or get off the pot.
3. I sank 15 pots at the pub last night.
4. I don’t know what Holden were thinking when they put an eight-pot donk in a Torana.
5. Paul Chapman potted 4 goals for the Cats today.

[ via http://www.urbandictionary.com/define.php?term=pot ]