A brief review for the benefit of Brendan et. al.:

sar·casm
/sär,kazəm/

noun: sarcasm; plural noun: sarcasms

The use of irony to mock or convey contempt.
    "his voice, hardened by sarcasm, could not hide his resentment"
    synonyms: derision, mockery, ridicule, scorn, sneering, scoffing;

i·ro·ny
/īrənē/

noun: irony

The expression of one's meaning by using language that normally signifies the opposite, typically for humorous or emphatic effect.
    ""Don't go overboard with the gratitude," he rejoined with heavy irony"
    synonyms: sarcasm, causticity, cynicism, mockery, satire, sardonicism

sar·don·ic
sär/dänik/

adjective: sardonic

    grimly mocking or cynical.