I have a colleague who is a professional man in his thirties. We don't work together at all, but in three same company. If we did work together he'd be senior to me. He's friendly and likes to connect with people, will always ask people how they are, how their holiday was, likes to talk about his wife and child, etc. Can be a bit full on in an enthusiastic, but harmless way. A few days ago he waked past me. I knew he was coming, even though I wasn't looking in his direction. As he walked past he held up something next to my head (possibly a large book or a box) and slammed it shut. I didn't turn to look or react at. (My job is quite challenging at the moment and I'm having to stay incredibly calm and non-reactive, so that was the mode I was in) It was quite loud, and piled on quite a lot of sensory overload. I suspect my colleague expected me to jump. He said "No? OK then!", walked into his office and closed the door. He obviously wanted some sort of reaction. If he'd been an annoying 9 year old I'd have said a firm "No thank you." Several days later I'm still thinking "WTF?".