n. — informal
a nickname for British Columbia, especially Vancouver and the Lower Mainland.
La-la land originated as a nickname for Los Angeles, derived from the initials L.A. (see OED-3, s.v. "la-la land" [1]). Like much else that is Californian, it migrated north and is used to refer to British Columbia. However, even in BC newspapers, the term usually refers to Los Angeles or to other locations or signifies an irrational state of mind rather than a place, as in "the councillors are in la-la land".
See also COD-2, s.v. "la-la land" (3), which is marked "Cdn", and defined as "British Columbia" in general.