For some reason, his double seems to be able to express himself facially with much more ease than he can, and he's about to comment on how totally unfair that is when suddenly his double is invading his personal bubble and smacking him around.

"Ow!" he cries out instinctively, but then he realizes that...this doesn't really hurt all that much. "Hey, cut it out!"

Eventually the other Wirt backs off though, and the real one glares, as much as a wooden puppet can glare at anything.

"What-- What's wrong with you? Why are you trying to beat me up? What did I even do to you?"

In other words, Wirt uses LEER.