It doesn’t suit one, it isn’t to one’s taste. The ultimate origin of this term is not known, although it definitely is British. Tea had become an immensely popular beverage in Europe by the mid-eighteenth century, and the positive version—he or she is my cup of tea—was used from the late nineteenth century. The negative is slightly newer, from the 1920s. Josephine Tey used it in The Franchise Affair (1948): “Probably she isn’t your cup of tea. You have always preferred them a little stupid, and blonde.”