This is for the purposes of fiction, not for actual use. For actual use, the obvious answers can be found among the wide variety of actual lubes available.

Anyway, say I want my characters to have unplanned sexytimes. What could they grab for this purpose which might plausibly be laying around the house -- okay, spaceship, whatever -- due to another main function, but which wouldn't cause any particular grief, or throw the reader out of the story while they contemplate possible consequences.

Soap or shampoo always make me cringe as a reader. But perhaps a food product? Or petroleum jelly, maybe? less

. . . [i]because there just might be someone using your story as a "howto" (they don't have a shock and horror smiley).[/i]

Yeah, that's exactly the problem, because I've encountered people who thought porny fanfiction actually was a reliable how-to guide. There's a disturbingly funny story I'd share here, except that would immediately render my real-life information googleable to this entire forum, which, just, no.

Butter? Eek. I encountered the petroleum jelly option in a novel when I was a teenager, and remember the scene vividly, and therefore really don't want to go that route.

Crisco . . . I think I need to wander off to the kitchen and actually handle some Crisco, because as someone who never ever cooks, I'm not sure I even have an accurate impression of its properties in my brain.

I might have to find an excuse to send some coconut oil into space, that sounds nicely harmless. Thanks! less