Charlie and Brooke -- How Do You Say 'Warlock' In Spanish?!

Charlie Sheen and Brooke Mueller have officially left the country ... together ... and TMZ has learned the private jet carrying the twosome has touched down in Mexico.

The former couple hopped on the jet late Friday afternoon ... judging by the photo they posed for on the plane (above), they look like they're heading on their honeymoon all over again.

Charlie tells TMZ ... he decided to take Brooke on the trip as a reward because she's been, "busting her ass with the boys, and [she's] more sober and healthy than I've ever seen her."

As we previously reported ... Charlie has made it his personal mission to help get Brooke the treatment she needs to finally conquer her addictions.

Still, we gotta ask...