Complex sentence: After someone impersonated how Sinceer drank a lot, she got mad and then did an impersonation of Seezinz, where she stood up with her arms on her hips and said she was a nobody.
Split into simpler sentences: After someone impersonated how drunk Sinceer was, she got mad and then did an impersonation of Seezinz. She stood up with her arms on her hip and said she was a nobody.