Knocked me for six...

[sair5412]

Where does that saying originate from? My boyfriend has a hangover and keeps saying it!! Does he actually know what he is saying?

Also, what does "bottled it" mean, when someone backs out of a situation.

[Ethel]

'Knocked for six' comes from the game of cricket.

'Bottled it' I always thought was another way of saying 'lost his bottle'.

People talk of Dutch courage - being bolder and more courageous because you've had a drink. Lost his bottle of drink - lost his courage.

[Quizmonster]

From the early 19th century, the phrase 'no bottle' meant 'no good/useless' According to The Oxford English Dictionary that is probably the usage that gave rise to sayings such as 'lose your bottle' and, more recently, 'bottled it'. In other words, if you lost your bottle, you had become useless.
It may also be derived from the Cockney rhyming slang words 'bottle and glass' meaning 'bottom'...ie the 4-letter word that opens with 'a', ends with 'e' and has 'rs' between them! One old meaning of 'bottom' was 'staying-power/courage', so losing it meant your bravery had gone.
In either case, you have "backed out of a situation", as you say, Sair.