Agree to disagree
Stop arguing because there is no change of agreement
A piece of cake
Something very easy to do
As a last resort
When all else fails
A pain in the neck
An annoying person
A bit of a dark horse
A person with hidden abilities
a fish out of water
somebody who feels uncomfortable
A bear with a sore head
irritated sore mood
A bitter bill to swallow
a difficult fact to accept
As the crow flies
In a direct line or route
A red rag to a bull
Something that is likely to provoke
Achilles heel
Someone’s vulnerability
A memory like a sieve
A poor memory
A sitting duck
An easy target
A storm in a teacup
A lot of fuss about something that is not important
An old wife’s tale
false belief
A night owl
A person who stays up late
Above board
Honest
A wild-goose chase
A hopeless search
All along
from the beginning to now
At close quarters
From a short distance
a dogs life
a difficult hard life
A long shot
a wild guess or a risk
a red~letter day
A very important day
a different kettle of fish
a totally different situation from the one that was just mentioned