What has many keys but can’t open a single lock?

I am a type of word that is spelt incorrectly or used differently, on purpose for humour. What am I?
Hint 1: You can find me in a joke.
Hint 2: I am a play on words.

John replied, when asked how old he was. In 2 years he will be twice as old as he was five years ago.' How old is he ?

Can you think of a smallest +ve number such that if we shuffle the digits of the number, the new number becomes double the original number?

In the given picture, in how many ways can you read the word "Tiger"?

Andrew’s doctor gives him three pills and tells him to take one every half hour. How much time will have passed by the time Andrew’s taken all three pills?

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

Why are all black people so quick ?

What can you hold in your right hand, but never in your left hand?

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?