here some for your reference : 1) 洗手间 --- it is polite expression always we used 2）厕所 ----- we use it often but we suggest use 洗手间 if some public and formal places ,such like restaurant, office 3）方便一下 ----- polite expression 4）大号 -------- bowel movement ,just use it in oral but don't use it in public place 5）小号 -------- pee ,just use it in oral just use it in oral but don't use it in public place 6）大便 or 便便-------bowel movement .it is old usage ,always children use it now 7）小便 or 尿尿-------pee . it is old usage ,always children use it now