Right after I graduated college I did temp work. One job was in an accountant's office. He was a great guy to work for, treated everyone really well, bought us lunch frequently, and was very friendly and outgoing.

He also had a metal prosthetic hook for one of his arms.

One day he came by my desk to thank me for something, and he was reading some papers with one hand when he patted me on the back... hard... with the metal hook... In case you've ever wondered, those things HURT. I yelled out "Ouch!" and then froze when I realized what had happened. He was also frozen in horror. Neither of us said a word as he backed away slowly, both of us smiling awkwardly.

He apologized and we both thought it was funny but in the moment it was hilariously awkward because neither of us wanted to acknowledge what was happening.