Well, isn't that just a happy little question! The simile for "as stiff as a" can be "as stiff as a board." Just imagine a sturdy board that doesn't bend or move easily - that's how stiff something can be when we use this comparison. It's all about bringing a touch of imagery and creativity to our words, like adding a splash of color to a beautiful painting.
This is not a saying - it's a simile. Something is as stiff as a board, which is a stiff piece of wood. It's just a description. The term "stiff as a board" is used in many country's (in particular UK) to describe a person suffering aches and pains. Normally associated with muscular pain especially after periods of heavy work such as lifting and carrying.
Simile
A simile.
A metaphor
As quick as a wink is a simile. ----
It is a simile.
simile It is an example of a simile (uses like or as). A simile in itself though is a type of metaphor.
simile
that man
It is a similie as you are comparing (something) to how sly the fox is. A similie uses the words "like or "as".
simile