Who hasn’t, at some point or another, walked confidently into an office, talking loudly, only to realise that their co-worker is on the phone?
If you’re unlucky, it’ll be like an incident I had once at the family holiday house, where I walked into my parents’ room unannounced.
Not only does it avoid any scarring incidents, but it’s also just polite. Your boss will appreciate that extra little bit of class that comes from knocking gently before entering.
On the other hand, your minions will feel happier if you don’t just barge into their offices. Remember, you’re one of them! Until you get home to your Jetski, mansion and beautiful spouse, that is!