Strummin and Hummin
The act of a single individual playing the acoustic guitar and singing along at the same time. Usually in a casual setting such as campfire as opposed to a literal performance.
Danny - "What's up Man, what's crackin?"
Matt - "Not much, just drinking some beer, got some friends over just strummin and hummin."
Matt - "Not much, just drinking some beer, got some friends over just strummin and hummin."