Britney Spears’ upcoming guest spot on the sinking CBS sitcom How I Met Your Mother has sent Clueless star Alicia Silverstone ducking for cover. Alicia has dropped out of a scheduled appearance on the fourteenth episode of the series after refusing to star alongside Spear and her assortment of shaggy hair extensions.

“Alicia was really excited about appearing on the show, but when she found out she would have to share the spotlight with Britney she wasn’t too keen.”

“She knows that everyone would be going out of their way to look after Britney, and it would be so chaotic nobody would look after her,” a celebrity snitch spills to E!

Alicia will be replaced by Scrubs star Sarah Chalke in the episode, in which Britney plays “sweet and nerdy” secretary Abby.