I've only once hung out with colleagues after work so far, which was when we all went for dinner.
Or that's what it was originally supposed to be. It turned into 'Borrelen' instead and lasted the entire evening. I don't think there's an exact translation for 'Borrelen' in English. English is really lacking huh... there are quite a few Dutch words that don't have an exact translation in English. 😌
It's basically just like eating snacks and drinking something in a very informal atmosphere. With lots of talking.. and I'm not big on talking lots personally so I didn't say much =P