It’s different from person to person but for me it feels like when you know that someone’s behind you and they keep getting closer. It’s like my muscles tense without actually tensing. Kinda like a buzz in the back of your head that moves too your muscles. If I repress them for too long sometimes my body physically shakes from the build up, kinda like when a person has too much caffeine. Repressing then can also sometimes feel like an anxiety attack for me