TV
Will, changing the look not an idle threat with you.
— Xander ‧ Buffy the Vampire Slayer
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Xander treats a change of appearance as a threat worth taking seriously. The joke lies in calling something as ordinary as changing a look an effective warning: with this particular person, he suggests, it would be more than empty talk.
Context reviewed