There's an ugly new twist in Nas's ongoing custody battle with Kelis.

Apparently, Kelis is taking her milkshakes (and their nine-year-old son Knight) to Colombia where she and her new husband are going to be farmers.

That sounds like a terrible plan, and it may also be in violation of her custody agreement with Nas. She's already spent the Christmas holiday in the South American nation with Knight and has pulled him out of his private school in LA.

Nas now wants a judge to find Kelis in contempt, which would forbid her from moving Knight out of the country.

Nas has long argued that Kelis makes it hard for him to see Knight and the pair has been in and out of court for years.