What does this rebus mean?

O
N
C
E
TIME

A man walked into a pub and went straight towards the Barman. He asked for a dirty martini from the Barman. The Barman thought something and then pulled out a pistol from his drawer and aimed it directly at the man. Why did he do that?

Most people think of me as money. But when they find me in the water, they won’t get any money out of me. What am I?

Remove two matchsticks to make the below equation correct.

What kind of band never plays music?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

Can you solve below mathematical equation?

2^1234 - 2^1233

A bus driver was heading down a street in Mexico. He went right past a stop sign without stopping, he turned left where there was a "no left turn" sign, and he went the wrong way on a one-way street. Then he went on the left side of the road past a cop car. Still - he didn't break any traffic laws. Why not?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C