Sideways here we come

Nice mention of Personal Days on this podcast about language, for PRI's The World—but what is an "un-Eating Sideways" moment?

A short plug here for Ed Park’s novel, Personal Days. The book is replete with inventive wordplay (unwanted backrub given by a character named Jack = jackrub; character called Graham with whiny British accent is renamed Grime). Plus, there’s a nice un-Eating Sideways moment. It’s when the narrator suggests that there should be a French expression, along the lines of l’esprit d’escalier, for the sensation of being initially amused but later unnerved by something that’s said to you.