Idiom: "Give my best to someone"

Meaning: Please convey my good wishes to a particular person.

For example:

- Ahmad asked his friend to give Ali his best when they met at street.

Meaning in Arabic:
يُبلّغ أطيب أمنياته لشخص ما

Proverb: "STILL WATER RUNS DEEP"

Meaning: people who are calm and tranquil on the outside, often have a strong, "deep" personality.
Meaning in Arabic:

ياما تحت السواهي دواهي

O.K!!

During historic civil war's , when troops return without any casualties, a writing was put up so all can see which read "0 Killed", From here we get the expression "O.K." which means all is good.