According to OK! magazine, Britney had been in a huge fight with FedEx the day that she now-infamously shaved her hair off.
"They had a huge argument. Kevin threatened Britney that he was going to have people test her hair to find out exactly what she's been up to. She was so scared. That was what made her have her head shaved."
Although I guessed the drug-testing threats were coming from her record label, I totally called this one.
Brit's at Promises Malibu, being mercilessly stalked by paparazzi, who have already scored pics of her in the courtyard. More pics here.