Polishing Turds

This is an expression (polishing turds) used mostly in the Software Industry in the UK and means to make a piece of poorly written and virtually unfixable software appear to function by giving it a smart user interface. I could mention a well know operating system which is a prime example of where this technique has been used but they might sue me so I'll keep stum.

Another term: put more lipstick on the pig.

"Keep stum"?

What's that mean?