Characters
Come on in, and try not to ruin everything by being you.
— Carol · As Good As It Gets
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
A welcome and an insult arrive together: the speaker invites the visitor inside while warning them not to spoil everything just by being themselves. The barb suggests that the person's personality is the problem, and the courtesy of the invitation makes the criticism sting more.
Context reviewed