What does this rebus mean?

O
N
C
E
TIME

What came first, the chicken or the egg?

What can you catch but never throw?

Why is 6 afraid of 7?

How old is your son? asked a man to his neighbour. My son is five times as old as my daughter and my wife is five times as old as my son. I am twice as old as my wife whereas my grandmother, who is celebrating her eighty-first birthday is as old as all of us put together.

How old is the man's son ?

Mr Red Lives in the red house.
Mr Green Lives in the greenhouse.
Mr Yellow Lives in the yellow house.

Who lives in the Whitehouse?

Decode below rebus
D
N
A
T
S , D

A horse was tied to a rope 5 meters long and the horses food was 15 meters away from the horse. How did the horse reach the food?

A man says, "Brothers and sisters, have I none, but that man's father is my father's son." Who is that man?

What's a single-digit number with no value?