Commonly-Used Idioms, Sayings and phrasal verbs - "J" Idioms. What is the meaning of idioms? Words that come together and change the whole meaning of the statement like "it rains cats and dogs", did you ever seen cats and dogs falling off from the sky?! Of course not, but it simply mean "it is raining too hard". | J a jack-of-all-trades - a person who can do many things We gave the man a job because we needed a jack-of-all-trades to look after the many repairs. jack up something - raise prices raise something with a lifting device The gas station jacked up their prices during the snow storm. We jacked up the car so we could change the tire. jam on the brakes - quickly put the brakes on in a car to stop He jammed on the brakes and was able to avoid hitting the child. jam-packed - crowded full The train that we took this morning was jam-packed with people. to jazz up something - brighten up something add more noise movement color to something They jazzed up the community center for the party tonight. Jekyll and Hyde - someone with both an evil and a good personality My co-worker is like Jekyll and Hyde. One minute he is very friendly but the next minute he is angry. 418 Mr_doody2004@ jockey for position - try to push one s way into an advantageous position Several of the salesmen began to jockey for position when they learned that the director of sales was leaving. jog someone s memory - stimulate someone s memory to recall something The questions that the police officer asked helped to jog the man s memory. John Doe - a name used for an unknown average person The application forms use the name John Doe as the name of a person who is applying for something. John Henry John Hancock - one s signature Please sign your John Henry here and we will process your order right away. Johnny-come-lately - a new-comer He s a Johnny-come-lately and doesn t really know what he is talking about. Johnny-on-the-spot - someone who is at the right place when needed or is right on time He is always Johnny-on-the-spot. Just when we need him he arrives. 419 Mr_doody2004@ join forces with someone - unite join with someone The two high schools joined forces to try and raise money for the city library expansion. join hands - hold hands with other people Everybody in the group joined .