Adjective.
Definition 1: A complimentary statement of one's posterior.
Synonym:
Bootylicious
Definition 2: A durogatory comment regarding someone who excels at being a fantastic asshole.
Synonym: Colossus Assholus
Example 1: "Gee, these pants
make my rear
end look asstastic!!"
Example 2: "My
ex was asstastic, he left me destitute."