Year in year out
Year by year. Many years consecutively.

Year round
All year/ the whole year

Yellow billed
Coward

Yello press
Bias media. Media who report with no mercy.

Yes and no 
Unclear / not confident

Yes man
Someone who always agree with other people

Yesterday's man
Someone who has been overlooked because he is not as successful as his old time

You are toast 
Your are in a real trouble

You are what you eat 
The food you eat is very important for your health

You bet 
Totally agree

You can say that again 
Totally agree

You cannot unring a bell 
You cannot recall something which you have done

You could hear a pin drop 
Very quiet

You name it. 
To give a total credit to someone on something (it).

Young blood 
New generation people

Young turk 
Group of activist usually form by old belief.

Your call
Totally your decision

Your name is mud
Bad reputation

Yummy
Delicious