When you ‘make a mountain out of a molehill’ it means that you exaggerate an unimportant matter, or in other words you turn a small problem into a big problem.

Another English idiom ‘to blow something out of proportion’ can be used in this case to express the same thing.

To say that a person has gone nuts means that they have become completely crazy, foolish, eccentric or mad.

“It is so busy here that I think I will go nuts.”

If you are determined to obtain or achieve something at all costs, you want it regardless of the expense, effort or sacrifice involved.

“The journalist was determined at all costs to get a report from the war zone.”

The punch line is the funny sentence that ends a joke or an amusing story.
“When my dad tells jokes, he never gets the punch line right!”

If someone has a change of heart, they change their attitude or feelings, especially towards greater friendliness or cooperation.
“He was against charity, but he had a change of heart when he saw the plight of the homeless.”

When something goes downhill it deteriorates or gets worse little by little.
“The restaurant has been going downhill since the arrival of the new owner.”

If a person has the best of both worlds, they have the benefits and advantages of two different things.
“We live in the centre of town, but only 5 minutes from the beach. We have the best of both worlds.”

If a person does something come rain or shine, they do it regularly, whatever the circumstances.
“He goes to the gym club every day, come rain or shine.”

Someone who is chasing their (own) tail is spending a lot of time and energy doing many things but achieving very little.
“He’s been chasing his tail all week collecting data but the report is still not ready.”

If you turn a blind eye to something, you pretend not to notice what someone is doing.
“The woman turns a blind eye when she sees children taking apples from her garden.”