Cinta:	Rylan, ¿conoces la expresión Aquí hay gato encerrado?
Rylan:	Hmm... Aquí hay gato encerrado. No, no me suena.
Cinta:	¿No te suena?
Rylan:	Para nada.
Cinta:	Yo un día encerré el gato de una amiga mía en el cuarto de baño porque yo quería hacer yoga y él quería jugar, así es que decidí encerrarlo en el cuarto de baño.

The expression ¡Aquí hay gato encerrado! is used in situations in which there is a hidden factor that prevent us form knowing what's really going on. Therefore, it becomes a mystery, because it cannot be fully understood; something doesn't make sense. Normally is something negative that someone is trying to hide for unknown and unclear reasons. The English equivalent is There is something fishy!

The origin of the expression "haber gato encerrado" comes from ancient times when people wore "monederos" (change purses) which were made from cat skin and they hid them underneath their clothes to protect their money from being stolen. So literally, "the cat was hidden". Another definition for the word "gato" also included in the dictionary is bolsa para guardar dinero.

Dar mala espina, is another common expression whose meaning is very similar to haber gato encerrado. Literally, To give a bad thorn, has no meaning at all, but figuratively it is said when someone has the feeling that something is wrong and suspects that he or she could be the victim of a scam, and somehow could get into trouble. If for example, you are about to purchase a very expensive work of art which the art dealer assures you that is a unique and authentic piece from the Roman times, and then you see a small label at the back that says: "Made in Spain." In this scenario, one can say: Me da mala espina. - I smell a rat!