I have a totally honest question as a now atheist ex-catholic: what the hell is this catholic guilt everyone mentions here?! I truly don't know what this means, as it seems to refer to a rather specific kind of guilt unique to catholics and I apparently was never taught about it or have since... forgotten it?

I was raised catholic by two catholic parents, but both are left-wing/liberal, pro-choice, vote Democratic consistently, etc. I attended K-8 at two catholic grade schools in a liberal part of Wisconsin, USA, then did CCD in high school. But I don't really know what this catholic guilt concept is.

Admittedly, I don't have any horror stories of catholicism unlike so many here; I left after questioning the logic behind the concept of a god, before being pushed to the edge after the CCD director answering a question in a completely disgusting manner.

Is there a universal definition? Or does it vary by person?

Edit: Thank you for the answers everyone has provided, and the personal experiences shared. This is eye opening for me, lacking the harsher experiences many of you suffered. It provides a very different perspective on why I left the church and became atheist: my choice is more about a lack of interest in the concept of a god(s) and finding no logic in the concept of the supernatural. The more abuse stories I read and hear, be it the horrible sexual and physical abuse at the hand of priests to the mental and psychological abuse suffered from the teachings, the more I see how I saw a facade growing up, with the true church coming out now.