The word crazy is an adjective. It has two general definitions, and it is used in a wide variety of expressions!
1. mentally ill
The old definition of crazy was someone who had a serious mental illness and was not sane. Nowadays it is considered offensive to call someone who has a mental illness ‘crazy.’ At the same, if you want to insult someone by implying that they have a mental illness, you call that person ‘crazy.’
Have you met her new boyfriend? He’s crazy! He’s got serious mental problems. I wouldn’t go anywhere near him.
2. something or someone that is stupid, not sensible, uncontrolled, wild, foolish, unreasonable, strange, unusual
She always wears the craziest outfits!
Is this another of your crazy ideas?
You went skydiving?! Are you crazy?
= to become any of the about definitions of crazy!
= to become mentally ill, out of control, etc.
I think I’m going crazy!
The crowd at the baseball game went absolutely crazy when the batter hit a homerun!
We were sitting quietly watching TV when all of a sudden the dog went crazy! He just started barking at the TV and running around the room.
= You become stir-crazy when you become bored, impatient, restless, upset, and uncomfortable from being stuck inside or stuck in one place for a long time, from being inactive, or because you are prevented from doing something for a long time.
Her doctor has restricted her to bed rest for the rest of her pregnancy. She is going stir-crazy.
His car is being repaired so he’s been stuck in his house for the past couple of days. He’s starting to go stir-crazy!
to be crazy about (something)
= to be interested in or like something/someone intensely
= to be very enthusiastic about something/someone
My daughter is crazy about the Jonas Brothers! She listens to their music all the time and has pictures of them all over her bedroom walls.
Jane and Matt are completely crazy about each other. They love each other so much!
to drive (someone) crazy
= to make someone angry by annoying, irritating or bothering them
We get so many phone calls from telemarketers, it drives me crazy!
His wife’s constant nagging is driving him crazy!
Our neighbour’s dog is always outside. His loud barking drives us crazy!
(do something) like crazy
= to do something very quickly, very energetically, and to do a lot of it!
She has been cleaning her house like crazy!
The project deadline is in 4 days so the whole team is working like crazy to get it done on time.
Rihanna’s new album is selling like crazy!
*This is expression is similar to doing something as if / like it’s going out of style.