Saying Goodbye
One of the most awkward things can potentially saying goodbye to people. Some things that come close: Extra long handshakes or hugs, when you to do the side-to-side dance when you walk towards someone, or when you respond to a "How are you?" and the person has walked too far to hear your genuine reply.
But saying bye can be extremely awkward for some people. First of all, there's numerous way of saying bye: Peace/Peace Out/Good Bye/Bye/Bye Bye/See Ya/See You Later/See You Another Time etc. Sometimes I go to say one thing and then change my mind in the middle. Some people say bye and they speed off while others do the "good bye dance". Everyone knows those people who can't seem to leave and often say bye on multiple occasions.
For me, I don't know what action is "correct" in some situations. Is a hand-wave good enough? Professionally, a handshake is the standard routine. How close do you have to be with someone to do the hug? It's all just a huge mess. It's even worst when you know you won't see someone for a long period too.