Here the verb ‘to cry’ means ‘to offer for sale in the street’. Barrow-boys
cry fruit: ‘Fine ripe strawberries!’ Flower-girls cry flowers: ‘Lovely
violets!’ Fishmongers cry fish: ‘Fresh-caught mackerel!’ But they and others
of their kind would not find many customers if they condemned their own wares
– ‘Overripe strawberries!’ and so on.

By extension, to cry stinking fish is to belittle one’s own efforts; to speak
unfavourably of what one has to offer to others. For example, a young author
sent his first novel to a firm of publishers with a covering letter admitting
that the grammar was faulty, the construction weak and the plot unoriginal,
but he hoped they would accept it for publications. We wonder if they did! Of
course, to go to the opposite extreme can be even worse.

##### See also:

* Don’t make yourself a mouse, or the cat will eat you
* Make yourself all honey and the flies will devour you
* Self-praise is no recommendation