What are your favourite Latin phrases?

[Dictator]

In vino veritas, in aqua sanitas.

And that's why I do not drink.

[curupira]

O tempora o mores!

"O tempora o mores" is a sentence by Cicero in the fourth book of his second oration against Verres (chapter 25) and First Oration against Catiline. It translates as Oh the times! Oh the customs! (Oh what times! Oh what customs! or alternately, Alas the times, and the manners) It is often printed as O tempora! O mores!, with the interposition of exclamation marks (not present in Classical Latin).

In his opening speech against Catiline, Cicero deplores the viciousness and corruption of his age. Cicero is frustrated that, despite all of the evidence that has been compiled against Catiline, who has been conspiring to overthrow the Roman government and assassinate Cicero himself, and in spite of the fact that the senate has given senatus consultum ultimum, Catiline has not yet been executed. Cicero goes on to describe various times throughout Roman history where consuls have killed conspirators with even less evidence, sometimes – in the case of former consul Lucius Opimius' slaughter of Gaius Gracchus (one of the Gracchi brothers) – based only on "quasdam seditionum suspiciones", certain suspicions of insurrection (Section 2, Line 3).

This sentence is now used as an exclamation to criticize present-day attitudes and trends, often jokingly or wryly. One example is by the musical comedians Flanders and Swann, where Flanders proclaims "O tempora, O mores - Oh Times, Oh Daily Mirror!" The expression is used in the play and movie Inherit the Wind, a fictional account of the Scopes "monkey" trial. The phrase is uttered by the cynical reporter, Hornbeck, and refers to the town's backward attitude towards enlightened thinking (here Darwin's theory of evolution).

http://en.wikipedia.org/wiki/O_tempora_o_mores!

[morski]

Trans penem mihi est.

Ego sum qui sum.

Nil satis nisi optimum.

[Borna]

When i sniff cocaine, its "Nula dies sine linea"

[Sylvanas]

Cogitationes posteriores sunt saniores.

Varitatio delectat.

Historia est vitae magistra.

Exceptio probat regulam in casibus non exceptis.

[Mikula]

Qui custodiet ipsos custodes?
Who watches the watchers?

[Andullero]

Ultima Ratio Regum = The last argument of the kings, a motto that used to be inscribed on all the cannons of Louis XIV's armies.