So why on earth would you say about a combi that it is “soup”? (está sopa means it is soup when translated literally)
Questioning of my friends revealed that it means that a combi is totally full, so full that not a soul extra would fit (so in a combi made for 30 people, 60 are already inside).
Allegedly this refers to the practice of making rich soups and filling them up with meat and vegetables until the rim, until really no more could possibly enter. So the next time you hear about a combi that it is sopa, you know that you should wait for the next one!