Oh, these work for us too.
I lived with an SO who had no idea for the longest time. When I was newer lady, I slipped up a few times.
He borrowed my car to run to the store once. He needed a pen to jot something else down on a list of errands or something. He opened my glove compartment to search for one... and oops, a small container of lubricant that we don't use. Man, that was the phone call from hell. I had two of my girlfriends cover for me. One made up a story about how they'd used it to prank me or some stupid bs. It was helpful, but I still had to explain why I even had lube at all to them, which was harder than talking my way out of it with the (now ex) SO. Women, as you know, are much nosier.
All should take courtesy showers before they play, even ladies. Every now and then, if I'm comfy with a gent, meaning we've seen each other before... and I have a flat or curling iron handy, I'll take one with him. It's always a fun start to the sesh!
I disagree with the bartering rule. Hahhh. I've gotten some great things that I would've bought with cash anyway from the barter system. Plus, it's always fun to giggle and smirk about your "GREAT HOOKUP."