Perhaps you do not understand sarcasm.
You must have missed that in high school. Here is the definition:
sar•casm P Pronunciation Key (sär k z m)
n.
1. A cutting, often ironic remark intended to wound.
2. A form of wit that is marked by the use of sarcastic language and is intended to make its victim the butt of contempt or ridicule.
3. The use of sarcasm. See Synonyms at wit1.
[Late Latin sarcasmus, from Greek sarkasmos, from sarkazein, to bite the lips in rage, from sarx, sark-, flesh.]