Safe and sound
Completely save
Salad days
The awkward old time which could be happy to think of.
Salt of the Earth
People who dedicate their life to make the world better.
Salty dog
An expert sailor/ fisherman
Save face
Save the reputation from public
Save your skin
Stay away from problems
Sea legs
Do/ try something new.
Second to none
The best
See eye to eye
Two or more people are agree on something
See red
Very angry
Seed money
First amount of money to start your business.
Sell down the river
Betray. Not follow agreement.
Sell someone down the river
Betray someone
Shake a leg
Hurry up
Shoot off the mouth
Show opinion very loudly
Shot in the dark
Do something with little direction and hope to be successful.
Sit on the fence
Does not want to make the decision
Slip one's mind
Completely forget something
Smell a rat
Compete with someone
Snow job
Dishonesly talking
So to speak
Refer to someone's speech
Sooner or later
In the near future
Slip one's mind
Completely forget something
Speak of the devil
Someone you are talking about (probably in a negative way) is arrived.
Stand me up
Miss an appointment with me.
Stick out the neck
Take the risk