"I dunno, how hard is it to find somewhere else to sit?" Now he's actually starting to get annoyed. How dare someone expect him to do something pretty simple that he doesn't want to do.

"Tell you what, you tell me why I should move, and maybe you can convince me." Probably not, though, that would involve Gajeel being a reasonable individual. But his tone doesn't do anything to mask the fact that this was never intended as a serious suggestion; he's pretty much just mocking Chris.