“Glad-hand” (or “to glad-hand someone”) means to greet people in an overly warm, enthusiastic way, usually because you want their approval or some advantage, and it often feels insincere or just for show.

In practice, it is often used about:

• Politicians or public figures smiling, shaking lots of hands, and chatting to win support.

• Anyone giving a big, performative welcome that seems more about image or self-interest than genuine feeling.