It's tricky to answer definitively without knowing which specific episode you're referring to. The Big Bang Theory had a lot of animal encounters, but blue jays aren't a common sight in Pasadena, California, where the show was set.

To help me figure it out:

* What episode are you thinking of? Maybe the plot involved birds or a specific bird encounter.

* What did the bird look like? Was it large and blue? Did it have a distinctive crest?

With more information, I can try to confirm if it was a blue jay or another type of bird.