Magic Johnson to Ex-"Employee" -- You Got Fired 'Cause You Sucked at Your Job!

Magic Johnson is whipping out a full court defense -- claiming the ex-flight attendant who's suing him for wrongful termination wasn't canned for her old age ... she was just TERRIBLE at her job.

As TMZ first reported, over-40 flight attendant Lanita Thomas claims Magic unfairly fired her earlier this year after 8 years of service on his private jet ... all so he could hire a much younger woman. Lanita sued for age discrimination and a slew of other things.

In his response (filed earlier this week in LA Superior Court) Magic claims Lanita's termination was because she started sucking up her job ... not because she got old.

Specifically, Magic says, "[Lanita] failed to use ordinary care and diligence, or exercise a reasonable degree of skill [in her employment] ... she failed to perform her job duties ... and failed to substantially comply with all directions concerning her employment."

Magic also says the suit is "frivolous" because Lanita was employed by Clay Lacy -- the company responsible for staffing his jet -- and thus the decision to axe her was NEVER his.