Jack of all trades:
Somebody who can do many different kinds of jobs.
He can fix the refrigerator, balance the company's checkbook, and cook gourmet food. He really is a jack of all trades!
Jam on your face:
When somebody is embarrassed or has been caught doing something wrong.
The student had jam on his face when he was caught going through the teacher's desk.
Jane/John Doe:
The name given to a deceased person at the hospital or during legal proceedings.
The police found the body of John Doe after midnight last night.
Jaywalk:
Cross the street outside of the marked area or without using the signals.
Police don’t like it when you jaywalk.
Jet setter:
Someone who travels around the world in airplanes to attend parties and functions.
I'm a jet setter. I will be at another party tomorrow night on the other side of the world!
Jockey for position:
When many people are competing to prove that they are the best candidate for a position.
All the new employees are jockeying for position because they want to impress the boss.
Jog my memory:
To help someone remember something.
I can't remember the last time we saw each other. Can you jog my memory?
John Hancock:
A signature.
Please put your John Hancock at the bottom of the contract.
Joshing Me/You/Him/Her/Them (like my name, Josh Shaman):
Joking with. *NOTE* This isn’t a common idiom, but people say it to or around friends named Josh.
He’s just joshing you! Don’t worry about it.
Jump the gun:
To start something too soon or early
I don't want to jump the gun and leave my current job until I know I have a position at the other company.
Jump through hoops:
To make great efforts and do tasks to please somebody.
You have to jump through a lot of hoops to get that job.
Just what the doctor ordered:
Exactly what is needed.
A day off after all this hard work is just what the doctor ordered!