1) The Universe's equal and opposite reaction to Jack Black, in accordance with Newton's Laws of Motion.
2) New British slang meaning "to defecate".
1) Actual A Level Physics question from Specimen Paper:
"Name a particle-anti-particle pair?"
Accepted answers:
Positron and electron
Muon and anti-muon
Jack Black and Jack White
2) "Outta my way, I need a Jack White!"
by Bailey89 May 02, 2006
When the awesomeness of Jack White (musician) overwhelms you to the point where you can only see white.
by BluesFan0421 June 28, 2011
by Drewbud315 July 06, 2007