Why do people go to bed?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

John is looking at Jenifer, but Jenifer is looking at Jacob. John is married, but Jacob is not.

Is a married person looking at an unmarried person ?

Solve the equation by replacing the alphabet with numbers.

MOM + MOM + NO = BOOK=

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

Dwayne Johnson was running away with the loot from a heist in his car along with Vin Diesel. One tire was punctured and he dropped down to replace it. While changing the wheel, he dropped the four nuts that were holding the wheel and they fell into a drain. Vin Diesel gave him an idea using which they were able to drive till the rendezvous point.

What was the idea ?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?