Writers are often challenged with how to describe things and make a scene more real with details and yet how do you go about doing this while not breaking the spell the reader is hopefully in. One of the techniques that I like to employ is being a bit ambiguous versus giving very specific details. It doesn't work for every situation or every audience but it is fairly useful for most situations.
Why am I suggesting to be ambiguous? Well a lot of that comes from being too specific can sometimes alter the reader from being lost in the story to suddenly wondering what exactly a ten inch long by six inch in diameter mega cock would look like. When a writer gives numbers to a description, while you're giving someone an exact idea as to the object it can easily distract them. Also the problem with using measurements is that there are two systems of measurement in the world and the audience is global. Reading something in inches can easily make someone who is used to metric measurements stop reading your story in order to figure out exactly how that would look in terms of the metric system.
Instead of writing about exact details, giving descriptions like Jack's endowment was lengthy, well above average with an impressive girth to match, allows for the readers mind to shape the size the way they would wish to see it. More importantly it allows for uninterrupted story reading and keeping the reader within the realm of the story is what it's all about.
There are of course times where measurements are desired, some people are admittedly size queens and they may very well know the sizes they are necessarily looking for. This sort of situation falls under the idea of knowing your audience, if your targeted audience may be full of size queens then perhaps you'd be best putting in specific measurements in the system that they are most likely to be familiar with.
