Jim Parsons Spoils Kaley Cuoco's Birthday Cake Surprise In Sitcom-Like Flub

"Oops," the "Big Bang Theory" actor wrote afterward.

Jim Parsons may be a wonderful co-star for Kaley Cuoco on “The Big Bang Theory,” but he’s a lousy secret-keeper.

On Thursday, the sitcom actor shared a photo on Instagram of a surprise birthday cake for Cuoco. Only he mistakenly tagged her on the post, alerting her to the celebration afoot. Dude.

Parsons tried to recover with a quick “oops,” but it’s Cuoco’s deadpan reaction to the cake post that tells it all.

Cuoco, whose actual 33rd birthday fell on Friday, was definitely laughing on the inside. “ON THE FLOOR,” she commented in the post, per “Entertainment Tonight.”

We could totally see Parsons’ self-absorbed Sheldon character accidentally ruining a surprise birthday celebration for Cuoco’s Penny (heck, maybe it even happened in those 250-plus episodes). But in real life, it might even be funnier.