Up To Eleven Meaning

(idiomatic) Beyond the maximum possible threshold

Example: 1997, Matthew Branton, The Love Parade, Hamish Hamilton (1997), ISBN 9780241137574, page 60:
  She and River looked at me hard; but I lowered my eyes and leaned forward, with the nonchalance turned up to eleven, extinguished my cigarette, made eye-contact and nodded curtly.
2008, Tim Pratt, Poison Sleep, Bantam Spectra (2008), ISBN 9780553904734, page 267:
  Flying is like motion sickness turned up to eleven, […]
2013, Mark Mason, Move Along, Please, Random House Books (2013), ISBN 9781847947109, unnumbered page:
  As we reach the city today, rush hour has been turned up to eleven, so there's plenty of waiting in traffic.