The Intimate Adventures Of A London Call Girl, by Belle de Jour
Second paragraph from 'mars' [='March'] chapter, from the 'A-Z of London sex work' series of side-bars, discussing oil:
Aside from degrading barrier protection, it’s a rubbish lubricant in general. A man once suggested (whipping out a tub of Vaseline as he did so) attempting to fist me with a petrolatum-based aid. Are you joking? That stuff traps heat and makes it feel like someone’s deep-frying your labia.
This is a really funny and frank look at the high end of the London sex work market, by a scientist and feminist who ended up being played by Billie Piper on TV in her first major role after Doctor Who. I guess some readers will be disappointed to find that the sexual politics in the book is more prominent than the actual descriptions of the act, but if you want a provocative and witty read about sex and society, this is a very good place to start.