我们拆开这个词组 rich [rɪtʃ] adj. 有钱的, 富有的; 贵重的; 富于的, 有很多的; 富丽的 B + itch [ɪtʃ] n. 痒, 疥癣, 渴望 v. 发痒; 渴望; 使发痒; 使恼怒; 使烦恼; 搔 所以，这个词组的意思大概是 “有很多的（或者贵重的） B 发痒”

Well, this is a little bit embarrassing as Eliot pointed out.

A rich bitch is a bitch that is rich. It may refer to the "rich class" in Mainland China.