Had to put up the whole eleven exchange:
Nigel Tufnel: 'The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...'
DiBergi: 'Oh, I see. And most amps go up to ten?'
Nigel Tufnel: 'Exactly.'
DiBergi: 'Does that mean it's louder? Is it any louder?'
Nigel Tufnel: 'Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?'
DiBergi: 'I don't know.'
Nigel Tufnel: 'Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?'
DiBergi: 'Put it up to eleven.'
Nigel Tufnel: 'Eleven. Exactly. One louder.'
DiBergi: 'Why don't you just make ten louder and make ten be the top number and make that a little louder?'
Nigel Tufnel: 'These go to eleven.'