One of the strippers who posed with Katy Perry inside a Santa Barbara strip club has been FIRED for violating the Cardinal rule ... taking pics of their encounter and making them public.
Sources tell TMZ ... honchos from Spearmint Rhino's corporate offices marched over to the Santa Barbara location earlier this week and promptly fired Cassidy (her stripper name) in front of all the other girls.
23-year-old Cassidy -- pictured above on the right -- was one of the girls working Super Bowl night, when Katy rolled in with boyfriend John Mayer and dropped stacks all over the place.
Cassidy, Katy, and other dancers posed for several photos ... TMZ obtained the pics and posted them a couple days later -- and management was pissed.
We're told Cassidy -- who has a child -- violated her club's "no cameras" rule by taking the photos and making them public and that's why she got canned.
We're told Cassidy was fired in front of all the other girls to send a clear message ... don't mess with client privacy, or else.