Kaley Cuoco of the CBS comedy “The Big Bang Theory” will guest star on the season finale of “Grey’s Anatomy,” according to EW.

The actress, a self-proclaimed fan of the show, announced the casting  Thursday night at PaleyFest. Cuoco said she is set to film her part next week, although what exactly that part entails is still unclear.

“It’s a big ol’ secret. I have no clue what I’m doing,” she told the magazine. “My guess is that I will be a patient of some kind. I’m practicing my scared, sad ‘I’m dying’ face.”