HOW TO PROVE IT

Proof by Example: The author gives only the case n = 2 and suggests
  that it contains most of the ideas of the general Proof.
Proof by Intimidation: 'Trivial'.
Proof by Vigorous Handwaving: Works well in a classroom or seminar
  setting.
Proof by Cumbersome Notation: Best done with access to at least four
  alphabets and special symbols.
Proof by Exhaustion: An issue or two of a journal devoted to your
  proof is useful.
Proof by Omission:
  'The reader may easily supply the details'
  'The other 253 cases are analogous'
  '...'
Proof by Obfuscation: A long plotless sequence of true and/or
  meaningless syntactically related statements.
Proof by Wishful Citation: The author cites the negation, converse, or
  generalization of a theorem from the literature to support his claims.
Proof by Funding: How could three different government agencies be
  wrong?
Proof by Eminent Authority: 'I saw Karp in the elevator and he said it
  was probably NP-complete.'
Proof by Personal Communication: 'Eight-dimensional colored cycle
  stripping is NP-complete [Karp, personal communication].'
Proof by Reduction to the Wrong Problem: 'To see that infinite-
  dimensional colored cycle stripping is decidable, we reduce it to
  the halting problem.'
Proof by Reference to Inaccessible Literature: The author cites a
  simple corollary of a theorem to be found in a privately circulated
  memoir of the Slovenian Philological Society, 1883.
Proof by Importance: A large body of useful consequences all follow
  from the proposition in question.
Proof by Accumulated Evidence: Long and diligent search has not
  revealed a counterexample.
Proof by Cosmology: The negation of the proposition is unimaginable or
  meaningless. Popular for Proofs of the existence of God.
Proof by Mutual Reference: In reference A, Theorem 5 is said to follow
  from Theorem 3 in reference B, which is shown to follow from Corollary
  6.2 in reference C, which is an easy consequence of Theorem 5 in
  reference A.
Proof by Meta Proof: A method is given to construct the desired
  proof. The correctness of the method is proved by any of these
  techniques.
Proof by Picture: A more convincing form of Proof by example. Combines
  well with Proof by Omission.
Proof by Vehement Assertion: It is useful to have some kind of
  authority relation to the audience.
Proof by Ghost Reference: Nothing even remotely resembling the cited
  theorem appears in the reference given.
Proof by Forward Reference: Reference is usually to a forthcoming
  paper of the author, which is often not as forthcoming as at first.
Proof by Semantic Shift: Some of the standard but inconvenient
  definitions are changed for the statement of the result.
Proof by Appeal to Intuition: Cloud-shaped drawings frequently help
  here.
      (Originally from Kevin Lyda, State U of New York at Buffalo)