backslapper
/ˈbækˌslæpər/
noun
- A person who is overly friendly or enthusiastic in a way that seems insincere, often to gain favor.
- I prefer honest people to backslappers who pretend to be your best friend.
- The politician was known as a backslapper who shook hands with everyone at rallies.
- He's a classic backslapper, always laughing too loudly at the boss's jokes.