'Time is an illusion. Lunchtime doubly so.'
'Very deep,' said Arthur, 'you should send that in to the "Reader's Digest". They've got a page for people like you.'
Ford convincing Arthur to drink three pints in ten minutes at lunchtime

'This must be Thursday,' said Arthur to himself, sinking low over his beer, 'I never could get the hang of Thursdays.'
Arthur, on what was to be his last Thursday on Earth

'Ford, you're turning into a penguin. Stop it.'

'If there's anything more important than my ego around, I want it caught and shot now.'
Zaphod

'In those days spirits were brave, the stakes were high, men were real men, women were real women, and small furry creatures from Alpha Centauri were real small furry creatures from Aplha Centauri.'

In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.

Man had always assumed that he was more intelligent than dolphins because he had achieved so much... the wheel, New York, wars, and so on, whilst all the dolphins had ever done was muck about in the water having a good time. But conversely the dolphins believed themselves to be more intelligent than man for precisely the same reasons.

'A curse,' said Slartibartfast, 'which will engulf the Galaxy in fire and destruction, and possibly bring the Universe to a premature doom. I mean it,' he added.
'Sounds like a bad time,' said Ford, 'with luck I'll be drunk enough not to notice.'

'My doctor says that I have a malformed public-duty gland and a natural deficiency in moral fibre, and that I am therefore excused from saving Universes.'
Ford

'That young girl is one of the least benightedly unintelligent organic life forms it has been my profound lack of pleasure not to be able to avoid meeting.'