I wonder how the story continues... :D
Voi ei! Tuhmä koirä syö iso pihvi ;-D
Tuhma koira syö ison pihvin. :)
When do you use suuri vs. iso?
They are usually synonyms so both would work here. But "iso" refers always to physical size, while "suuri" can be used also more figuratively (a great man, a great act etc)
I reckon they are pretty much interchangeable, at least most of the time.
Suuri mies - a great man
Iso mies - a big man