waiting in the wings

meaning: waiting and ready to take over or act if needed; waiting and ready to take over a job once the current person leaves

1. They don’t need to worry too much: even if the boss leaves, they have Dave waiting in the wings, ready to take over.
wake-up call

meaning: an event that makes a person realise they have been completely wrong about something

1. I used to think everything in this city was perfect, but the walk through the ghetto was a real wake-up call.
walk a fine line

meaning: to have to be very careful in how you act because you are very close to annoying people

1. “At the moment she is happy, but I am walking a fine line with her husband: I think he is getting more annoyed with how much time she is spending at the office.”
a walk in the park

meaning: something that is very easy

1. The physics test was difficult, but the chemistry one was a walk in the park.
walk on eggshells

meaning: have to act very carefully, because someone may get angry

1. Every day I am around her I feel I am walking on eggshells; I feel she will kill me whenever I even make a suggestion.
walking encyclopedia

meaning: a person who seems to know everything

1. They won the pub quiz mostly thanks to Phil, who is a walking encyclopedia on all things trivia.
walking on air
meaning: to be so happy that you are in a good mood all the time

1. When Dave came back from his date with Anna, he was walking on air, with a big stupid smile on his face and singing an annoying tune.
war of words

meaning: a major disagreement, in which one person publically says an opinion, and the another person publically says an opinion

1. The film star and the journalist have been involved in a war of words since the bad review: first the journalist was ‘a talentless hack’, and then the actor a ‘wooden plank’. Now the journalist has been called ‘a leech’.
on the warpath

meaning: someone is very angry and actively looking for revenge or action

1. “Watch out, Mr. Jones is on the warpath. I’d stay away from the office for a while.”
(get) (your) wires crossed

meaning: to misunderstand someone’s message, getting the meaning completely wrong

1. Dave turned up for a meeting, only to find nobody else was there. Somewhere in all the emails he had got his wires crossed.

2. “I’m sorry, it seems I’ve got my wires crossed. I thought when you said you were going you were quitting the company, not getting promoted.”