1. The combination of the words thrash and fantastic, often used while discussing metal. This is not limited to metal, however. In order for a song to be thrashtastic, it must be fast-paced, contain some nasty riffs, or having powerful drums.
2. A word that indicates an exciting event that is taking/has taken place. This includes, but is not limited to: Parties, concerts, road trips, eating sushi, having sex, watching college basketball (or any other exciting sport), and fistfights.
1. Have you listened to this guitar solo? It is thrashtastic!
2. Hot damn; my girlfriend was absolutely thrashtastic last night.
Comes From Trash and Fantastic.... When your trash Your trash and you know it.... But sometimes people who are trash do not think they are they think they are fabuolous meanwhile they are just trash....