Charlie Sheen has been teaching his two-year-old sons how to say the word "rehab".

The troubled former 'Two and a Half Men' star -- who was fired from the sitcom after a fallout with co-creator Chuck Lorre over his drug taking and partying with porn stars -- has revealed he is trying to expand twins Bob and Max's vocabulary so they understand where there mother Brooke Mueller is.

Brooke recently entered rehab after refusing to take a court ordered drug test.

Charlie told TMZ: "I am teaching them words, because they're speaking now. I'm teaching them the word 'rehab' so they always know where their mom is."

Charlie -- who has three other children from previous relationships -- had hoped to win primary legal and physical custody of Bob and Max but had his plea rejected by judge Hank Goldberg at the Stanley Mosk Courthouse in Los Angeles.

The decision maintained the situation decided in court on March 10, which sees Brooke have majority custody of Bob and Max while Sheen will be allowed to spend time with them every other weekend from Saturday morning until Sunday evening for the first two months.

For the following two months, he will have the children every other weekend from Saturday morning to Monday morning. After that -- provided both he and Brooke stay alcohol and drug free -- he will have them an additional Wednesday morning through to Thursday morning.