Why is my social adeptness so polarized from place to place and person to person?

For example whenever I go to this acting class, especially if I’m talking in front of the class, I just start spitting without even thinking. I am extremely funny, interesting, charismatic. I can see people being entertained by me, the women attracted to me. It’s effortless. Another time I was at the gym and I was accused by a guy at the front desk of doing something that I didn’t do. He was with all of his friends but by myself I defended myself valiantly. I actually really enjoyed debunking him and then flipping him off. But around most other people/ places, even those I know well, I feel deep shame and anxiety. Nothing I say comes out right. I just know I am being perceived as weak, boring, insecure and that makes it even worse. It’s excruciating. I am effectively a completely different person depending on who I’m talking to and where. I seemingly cannot control it. I am an ENFP personality if that helps.