◎ 扒灰 páhuī
(1) [an affair between father and daughter-in-law] 公公与儿媳通奸
俗呼麀为扒灰。——明· 冯梦祯《快雪堂漫录·书王文旦事》
(2) 又清李元复谓爬行灰上则膝污,“膝”与“媳”偕音,故“扒灰”即“污媳”之隐语