Turnabout is fair play, I suppose.

Ms. Paragon of Virtue herself, Britney Spears, has been put through drug-testing, the loss of driving privileges and mandatory monitoring of visits with her two sons.

But she's decided to have K-Fed called on the carpet for allegedly exposing her kids to pot smoke. Britney plans to have her boys' hair samples tested to see if they've been exposed to marijuana.

According to a source, the pop tart "says she can smell it in the boys' hair and on their clothes when she has her visitation with them." A positive test could prove that 2-year-old Jayden James and Sean Preston, 1,  had been exposed to secondhand smoke and would probably lead to K-Fed's temporary custody being overturned.