He sniggered. He didn't like to think of himself as the sort of person who giggled or sniggered, but he had to admit that he had been giggling and sn… - Douglas Adams

There was an accident with a contraceptive and a time machine. Now concentrate!

Arthur shook his head and sat down. He looked up.
“I thought you must be dead …” he said simply.
“So did I for a while,” said Ford, “and then I decided I was a lemon for a couple of weeks. I kept myself amused all that time jumping in and out of a gin and tonic.

"Sir Isaac Newton, renowned inventor of the milled-edge coin and the catflap!"

"The what?" said Richard.

"The catflap! A device of the utmost cunning, perspicuity and invention. It is a door within a door, you see, a ..."

"Yes," said Richard, "there was also the small matter of gravity."

"Gravity," said Dirk with a slightly dismissed shrug, "yes, there was that as well, I suppose. Though that, of course, was merely a discovery. It was there to be discovered." ... "You see?" he said dropping his cigarette butt, "They even keep it on at weekends. Someone was bound to notice sooner or later. But the catflap ... ah, there is a very different matter. Invention, pure creative invention. It is a door within a door, you see."