What does the below image rebus riddle means ?

A Doctor always sneezes before the rain. Doctor sneezes, Will it rain?

What makes this number unique: 8,549,176,320?

Jim and Sarah are in a long-distance relationship. Jim buys an engagement ring for Sarah and wants to mail it to her. Unfortunately, the only way to ensure the ring will be received is to place a lock on the package. Jim has locks and Sarah has locks, but neither has keys for each other’s locks. How can they make sure the ring isn’t stolen?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

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

O T T F F S S ?

What is black when you buy it, red when you use it, and gray when you throw it away?

If you go to the movies and you're paying, is it cheaper to take one friend to the movies twice, or two friends to the movies at the same time?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

A man calls his dog from the opposite side of a river. The dog crosses the river without a bridge or a boat and manages to not get wet. How is this possible?