When a character in a TV or Movie pays homage to a character they previously played. Also can be coined when the show itself gives props to someone related to the show. Can also be used in Future context: During the Buffy series, there are no less than ten references to the Avengers comic books, and Xander even says "Avengers Assembe" twice. Later, the writer and director would go on to create one of the top-grossing films of all times, The Avengers.
Dirk Benidict playing Face from A-Team recognizing a Cylon in passing. He was totally Dejaviewing. Nathan Fillion as Castle dressing up as Captain Malcolm 'Mal' Reynolds from Firefly. In Burn Notice, someone called Bruce Campbell's gun a boom stick.