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 2, 2006
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When the awesomeness of Jack White (musician) overwhelms you to the point where you can only see white.
The amazing performance by the white stripes gave me a Jack White-out
by BluesFan0421 June 28, 2011
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