1. Expression：go to the John
Explanation：To go to the toilet. （上卫生间）
Example：I get runs so I've to go to the John.
In the restaurant, wait a bit before you go to the John.
She cannot feed herself or go to the John on her own.
A: I have to go to the John again. Wait me for a moment.
B: You are still so troublesome. Go quickly now, otherwise I’ll give you a knuckle sandwich.
A: OK. OK. I will be back soon.
2. Expression：John Hancock
Explanation：One's signature. （签名）
Example：As soon as you put your John Hancock on these papers, you'll be the proud owner of a brand new car!
I would never have put my John Hancock on such an unfavorable contract—I think my signature was forged.
The film fans gathered around him and asked her to put his John Hancock in their notebooks.
3. Expression：Big John
Explanation：A police officer. （警官）
Example：Hear those sirens? We need to get out of here before Big John catches us!
Big John came to our help when our car broke down on the way.
The supposed beggar was really Big John in disguise.