BYOB often appears at the bottom of invitations to private parties, most often from the poor impoverished invitors and every time you are invited to a student party. It means bring you own bottle/s, with bottles being easily translated as cans if that is how you like your beer. The idea is to bring something that you yourself would drink ¹ so that you won't complain to the host that there is nothing there for you to drink. After all you had been warned.

The Inverse Law of BYOB

This law states that no matter how much of you're favourite tipple you bring it will be consumed before you have had a sufficient quantity to feel a part of the party. The result is that you end up drinking other peoples tipples so that they too suffer from the same dilemma. As a result by 2am when the party is in full swing a bottle of malt vinegar is produced and consumed by the party goers, only to be heralded by the cry "I'm never buying that again".

The No Hiding Law of BYOB

Some devilish people and especially the host/s may try to conceal their favourite, and usually most expensive, drink somewhere secret. However once the Inverse Law comes into effect the hardened party goer will search out concealed supplies. This may happen accidentely by spotting the host taking a quick swig from a hidden bottle or deliberately searching through possible hiding places. Often if discovered accidently the spotter will promise the concealer never to reveal the location of the stash to anyone if they can just have one drink. DO NOT TRUST the spotter, within 2 minutes the remainder of the hidden stash will have been consumed by the whole of the party.