Why does Daniel's Ex Wife Says "Gordo" on the telephone

Main question: why does the ex wife says "Gordo" on the telephone?

Ok, just finished watching Amores Perros and something doesn't add up for me:

About 1 hour and 25 minutes, Daniel has a fight with Valeria when she says "I hope you never come back" then it shows Daniel in his office and he decides to call his ex wife. She answers it and he says nothing, she says "Hello?Hello?Daniel?"and then "Gordo? Gordo?" and then Daniel hangs up the phone.
I don't know in english subs if they change the characters names, but Gordo is the name (or nickname) of the character that organizes the Dog Fights and splits the profits with Octavio.
At the point of the movie i thought it would explain why the ex wife would say that but the part with Daniel and Valeria ended and nothing more is revealed.
So...Anyone know (or guess) what that is about?