Some of you may have seen those two words and wondered if they are synonyms.
The answer is: Yes, in the informal language “drin” is used instead of the more formal “drinnen”. Both mean “inside”.
But there is an informal expression which is widely used: “Das ist drin.” It means “Das ist möglich” (= Something is possible.)
In a funny way, you can say: Es ist heute zeitlich für mich drin, rauszugehen. (= My schedule allows me to go out today.)
Was ist für euch heute drin?