Prostate massage lubricant

Unless your family has KY Jelly just lying about, I think you are out of luck! Any household "lubricants" are different degrees of an irritant to the tissue around your anus and rectum. You are probably old enough to got to WalMart, Walgreens, Rite-Aid, etc to buy an over the counter lubricant. Since your prostate is about 2-3" inside your anus avoid anything that will cause irritation or an infection. Do not use hand cream because it has alcohol as an ingredient. If you should over stretch the spincter muscle that allows the anus to open and close, you will get a nice burning surprise! Play it safe and get a water soluable lube.

After making sure you are not allergic, try coconut oil. Cheap, natural, and easy to insert into the rectum (fill fingers of latex glove with liquid coconut oil, refrigerate glove and remove hardened coconut oil sepositories and push them into rectum. They melt back into liquid inside the rectum quickly due to body heat).

As far as I know, lubricant isn't an 18+ item. You can just walk into a pharmacy and buy it, it shouldn't even be expensive. 

Now that that's out the way, some people DO use alternatives to commercial lubricant. And yep, lubricant is especially important if you're going for a male prostate orgasm because the anus is so sensitive and you don't want to hurt it. So, I'm not sure how safe these are and I've never tried myself but some guys use aloe vera gel, natural oils like extra virgin coconut oil (definitely more expensive than run of the mill lube) and even egg whites (sounds gross). 

Hair conditioner. I started using it to masturbate when I was a teen, and i was also doing prostate stimulation with it. I still use it today at 28 years old for both. V05 I have found to be the best.