What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Why did the Girl throw the butter out of the window?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

Forwards I am heavy, backward I am not. What am I?

Why is it very easy to weigh a fish?

What has 13 hearts but no other organs?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

There were three women in all the swimming costumes!
One was happy and the other two were sad!
The happy one was crying and the sad ones were smiling.
Why was this?

I had an infinite supply of water and 5 litres and 3 litres jars.

How would you measure exactly 4 litres in the least number of steps?