Formal
正式
The following are appropriate in any situation:
下面这些表达适用于任何场合：
Bathroom
卫生间
Example: I’m gonna [going to] go to the bathroom.
例：我要用一下卫生间。
Restroom
洗手间
Example: Where is the restroom?
例：请问洗手间在哪?
Little boy’s/girl’s room
男/女厕所
Example: I’ll be right back, I need to use the little girl’s room.
例：我马上就回来，我想去一下洗手间。
Powder my nose
去洗手间(注：由女士去卫生间补妆引申而来)
Example: Excuse me, I need to powder my nose.
例：不好意思，我想去一下卫生间。
Familiar
熟悉
The following are appropriate with family or friends:
下面这些表达适合同家人或朋友说：
Pee
撒尿
Example: Where’ the bathroom? I need to pee.
例：卫生间在哪儿?我要尿尿。
Tinkle (mostly used by older women)
尿尿(一般为较年长的女性使用)
Example: I drank too much water! I have to go tinkle.
例：我喝了太多水!我要去尿尿。
Go (when used in context)
方便一下(在语境中使用)
Example: Where’s the bathroom, I really have to go!
例：厕所在哪，我真的要去方便一下了!
Potty (Generally used by children)
上厕所(一般儿童使用)
Example (noun): Where’s the potty?
例(名词)：厕所在哪?
Example (verb): Mama, I have to potty.
例(动词)：妈妈：我要上厕所。
Take a 1/2 (number 1 refers to peeing, number 2 to pooping)
大小便(1指的是小便，2指大便)
Example: Person 1 – I have to go to the bathroom.
例：甲——我要上厕所。
Person 2 – Number 1 or number 2?
乙——小便还是大便?
My bladder is bursting (when you really have to go)
我的膀胱要炸了(真的憋不住的时候使用)
Example: Stop the car! My bladder is bursting.
停车!我憋不住了。
Rude
粗鲁
The following are appropriate only with friends:
下面这些表达只能和朋友说：
John
茅坑
Example: Where’s the John? I have to take a number 2.
例：茅坑在哪?我要大便。
Loo (UK - can be familiar or rude, depending on where you are)
厕所(英式英语——根据不同的场合，这个词可以表现亲密，也可以表现粗鲁)
Example: I’ll be right back, I’m gonna go to the loo.
例：我马上回来，我要去厕所。
Crapper
厕所
Example: Hey man, where’s the crapper?
例：嘿，哥们儿，厕所在哪?
Take a leak
上厕所
Example: He has to take a leak, where’s your bathroom?
例：他要尿尿，厕所在哪?
Pee oneself (when you really have to go)
尿裤子(憋不住的时候使用)
Example: I’m about to pee myself, let’s go home.
例：我要尿裤子了，回家吧。
Can
厕所
Example: Do you mind telling me where’s the can?
不介意告诉我厕所在哪吧?
Vulgar
粗俗
The following should only be used with close friends, if ever. Also remember that it is more common for men to use these expressions than women.
可以的话，下面这些只能对最最亲密的朋友说。记住一般男性比女性更常使用这些表达。
Shit
拉屎
Example: Man, where’s the can, I need to go shit.
例：喂，厕所在哪，我要去拉屎。
Dump
拉屎
Example: He went to take a dump.
例：他去拉屎了。
Shitter
马桶
Example: I’ve gotta [got to] use your shitter.
例：我要用下你马桶。
Piss
小便
Example: We drank a lot of beer and now we all have to piss.
例：我们酒喝多了，现在要去小便。
Pisser
厕所
Example: Mind if I use your pisser?
例：不介意我用下你厕所吧?
Piss oneself (same as pee oneself, but cruder)
尿裤子(和pee oneself一样，但更粗俗一点)