Adopted a mannerism for his role in Gunsmoke

The guy was always tugging on his ear or pushing his hand over his mouth and mustache.
For a doctor, this isn't very hygienic, but that aside, it was an obvious mannerism he had to make his character more noticeable.

Doc Adams had a fun, irascible, cranky side to him we couldn't take seriously. He was smart and wanted his friends to take him into account, not just the wise and mild attending physician.
Then he'd rub his mustache, grab his ear, shake his head at how absurd everyone around him seemed. But he loved them dearly. What a nice character in a person.

I love you, I'm just not gonna show it. You'll have to figure it out.