WAY 1: Carry fresh panties on you at all times. This is so that if your feeling promiscuous on a day trip out, you can take the spare pair out of your bag and exclaim, "HEY LOOK MY BOYFRIEND, I've taken two pairs of underwear out with me!
He'll ask why, and you'll just wink at him.
This will suggest that you don't really know either but you've taken the effort to do so, so it must be a good idea.
WAY 2: Cry each time the sun goes behind the cloud and exclaim that each time it goes behind the cloud it reminds you of the time you put the fresh pair of panties in your bag.. He'll not only wonder why you're crying because of that, but he'll probably think it's slightly sweet/over bearing. It will make him want time away from you in which you can go on to FB and look totally hot etc, it will make him want you back, and that will keep the relationship fresh!
WAY 3: Buy a new hat. It will stop you from sweating, and you'll look like a fool most probably, but!!! this will work in the same beneficial factor as WAY 2 (see above) did. He'll hate it. And then on FB/bebo/myspace(?) He'll see how cool you look and will want you back in no time.