Below/above stairs British old-fashioned
(Below stairs) at or in the basement of a mansion, deemed as the area where the servant worked and lived.
This story gives me insights into the life below stairs at Buckingham Palace.
The rich kid wants to experience the life below stairs.
(Above stairs) on the upper floor of a mansion, deemed as the area where the owner of the house and his/her family resided.
The son of the servant asked him what the life above stairs looks like.
The servant is feeding the cat that belongs to the people who live above stairs.
The origin of this phrase is not clear.
People tend to like forbidden or illegal things just because they are forbidden or illegal.
He must have believed that stolen fruit is the sweetest, and he, therefore, cheated on his partner.