to render an entertainment (radio, television, film, book, play, etc) more sexually titillating UK, 1974.
2
to modify a recording to make it sound more 'authentic' or 'raw' US, 1983
dirty up
To soil or begrime something. A noun or pronoun can be used between "dirty" and "up." I'm not dressing the kids for church until the last possible second so that they won't have a chance to dirty up their clothes.
dirty something up
Rur. to get something dirty. Those pants are brand-new! Don't dirty them up!Don't dirty up your brand-new pants!