There is a section labeled Nonfiction, with titles like:

-True Secrets of the Nymphomaniacs: A Doctor Tells All
-My Life On The Isle Of The Lost 
-Marital Practices Among The Polynesians
-Predators Threatening YOUR Daughters: What You Need To Know To Keep Them Safe
-Improving Your Marital Bedroom
-Your Best Marital Life: With Detailed Case Studies And Anatomical Drawings

Okay, these are promising in that they imply there's something married people do in their bedrooms with their anatomy. That last one sounds the most potentially informative and hopefully any pictures are going to be the sort of pencil sketches you get in biology class and not something that would get banned on Earth for inspiring lust. He takes a look.

He opens to a picture of a naked woman on her knees before a man with his genitalia in her mouth.

Kaleva has wandered into the M/M section and has a look of shock on his face.

You can put--in your--whyyyyy? Has this book got a bloody index or something??? And oh no, Kaleva doesn't seem to have been having the best time either.

Also now there are all these images in his head and they're combining with the sight of Kaleva and the memories of the sauna in some sort of horrible mind-kaleidoscope. Bruce starts mentally reciting powers of two in the hope of rebooting his brain.

The table of contents says:

1. So You Want To Have Sex
2. The Male Organ
3. The Female Parts
4. Foreplay
5. Intercourse
6. Changing Positions
7. Orgasm
8. Spicing Up Your Sex Life
9. Oral Sex
10. Masturbation and Fantasy
11. Anal Sex
12. BDSM
13. Sex Toys
14. Miscellaneous

"Um. Kaleva?" he whispers.

"Yes?"

"I think it's the same as Earth. But with--more things." He doesn't know what all of those words mean and he's not sure he's going to enjoy finding out but not knowing is worse.

"Um, yeah. They uh. Know about men-- doing things-- with men."

"I got told that men shouldn't do--the things they do with their wives--with each other. But I don't know why they said that because it's not possible." He really wants to know what is possible and also he really wants to not be in a bookstore where someone might look at him. It feels like his thoughts are floating in the air over his head where everyone except him can see them and he's lost track of the power of two he was calculating.

"There's a book and it's, um. It's a story. About men doing things together."

"Do you think they'll let us buy these?"

"I'm not eighteen. --We could steal them."

It seems ridiculous to say "but stealing is wrong" when reading them at all is wrong, but. "Maybe we can just read them really fast and then put them back."

"Um. I think I might want to. Uh. Read mine thoroughly."

"Yeah, I want to read both of them . . . I guess you could leave some money on the shelf where they'll find it later. Or not, it's your money. And if you don't they might not notice anything missing."

"Yeah. We can. Grab some books and leave some money. --Do you want the M/F ones."

"Uh, just these two." He holds up "Improving Your Marital Bedroom" and "Your Best Marital Life" and then stuffs them down his shirt.

"Okay, I'll take"-- he grabs a couple of the fiction books and a couple of the nonfiction and as an afterthought one of the magazines, and then leaves some money on the bookshelf.

And they can get their ill-gotten gains out of the bookstore. Bruce has a lot of practice at not looking like he has a guilty conscience.

When they get back to the hotel room Kaleva kisses him. 

"My books. Were very interesting."

Kissing is nice in itself and also a reminder that they both have mouths. "Yeah?"

"--I don't really know whether I want to read them or whether I want to kiss you and work out what I can from what I read and worry about the rest of it later."

Bruce's brain has not even slightly stopped trying to produce Images. Also the books will still be there later but Kaleva wanting to kiss him still feels like an amazing opportunity that needs to be seized Right Now before it goes away. "Let's kiss first?"