crack open a window

To "crack open" a window means to open it a little bit. However, sometimes people say "crack open" just to sound cool, when actually they mean to open something completely.

Other things that you can "crack open" include:

Come on over! We'll crack open a bottle of wine and cook some steak on the grill.

I saw him crack open the door and look out.

get some fresh air in (a place)

"Fresh air" is air that:

• comes from outside
• is clean
• doesn't smell bad
• is dry and cool

Air that you breathe out in the countryside on a cool, sunny day is the perfect example of "fresh air". But if you're riding in a dirty car with no air conditioning in the summer, then you might call the air from outside the car "fresh", even if it's dirty and warm.

When people want to breathe fresh air, they say "I want to get some fresh air." If they're in a room or car, they might say "Let's get some fresh air in here."