Lighthearted abbreviation of the ever-popular English word 'bottom', used mainly in a humorous context. Can be used to literally mean 'one's bot-bot', but also subjected to frequent use as an adjective, describing physical features, clothes and unpleasant situations. It is also regularly used as an exclamation of dismay, in place of a more rudey swear word.
'PHWOAR look at his bot-bot.....'
'OH BOT-BOT I FORGOT ABOUT THAT FRENCH TEST!!'
'Rachel has a face like a bot-bot'
'This party is absolute bot-bot.'
'Kate likes it up the bot-bot'