PIMP: To make something better and more pleasing than it previously was. To change something for the better.
HACK: To change something without permission of the owner, or to change something from what it was meant to be.
MOD: To change or update something so that it is in tune with what is considered modern.
MASH-UP: Changing something so that it incorporates a variety of things. Giving something several different uses, so that it can be the all in one tool.

The words are really similar. They all have to do with change. The definition and connotation that follow these words have changed DRASTICALLY. It appears to be for the better. Society has seen a great shift in ideals among many other, and this seems to be evidence of that shift