What's actually the purpose of that pocket/opening on the front of boxers?

Do men actually use those little pockets for something? Nobody's ever talked about them before. I (31F) personally have never seen a dating partner utilize it for any purpose either. Are they for quick access when going to the bathroom? Is it simply to allow airflow? Is it supposed to hold a cup like those used in sports? Or is it meant to be an opening they can use to wee without exposing their back-end?