According to various sources, the flavor of the Fanta Mystery Halloween drink is still a mystery. However, some people have guessed that the flavor is blackberry or some other dark berry flavor. Others have guessed that it is orange or citrus-flavored. The drink is dark purple in color, which has led some to believe that it is grape-flavored, but this seems unlikely. The drink is also described as having a sweet taste. The Fanta Mystery Halloween drink is a limited edition, zero-sugar offering that is designed to trip up taste buds with a look and flavor shrouded in secrecy. It is also a 5D drinking experience that temporarily turns tongues black for a convenient complement to Halloween costumes.