Claudia, another answer to "in culo alla balena" is "speriamo che non caghi", or at least that's how we say in my area (Veneto-Friuli Venezia Giulia)! :)

Ciao, very nice article. I did't know how to translate some of them)).  The article is useful even for an italian haha)

Some of these expressions are used in spanish as well.

Le pegaron cuernos o le pusieron los cuernos. ( the cheating part) we even use the same hand gesture to symbolize the horns.

No veo en la hora. We use it more as a negative frase 

Very good article.