mystery guest

Noun

 * 1)  A person hired by a company to pose as a customer in order to evaluate the quality of its service.
 * 2)  A guest star whose identity is kept secret.
 * 1)  A guest star whose identity is kept secret.
 * 1)  A guest star whose identity is kept secret.
 * 1)  A guest star whose identity is kept secret.

Translations

 * Dutch: