Sardonic

Forced; unnatural; insincere; hence, derisive, mocking, malignant, or bitterly sarcastic; -- applied only to a laugh, smile, or some facial semblance of gayety.

Of, pertaining to, or resembling, a kind of linen made at Colchis.

disdainfully or ironically humorous; scornful and mocking; "his rebellion is the bitter, sardonic laughter of all great satirists" - Frank Schoenberner