From the Macquarie Dictionary:

sic (adv) so; thus (often used parenthetically to show that something has been copied exactly from the original).

That is why you will often see (sic) after a spelling or grammatical mistake in a quatation.

In Australia, "Sic 'im!" is also a command to a dog to attack somebody or something.

Again from the Macquarie:

sic (v.t.) 1. to attack (esp. of a dog). 2. to incite to attack (var. of seek)