Incremental
Don Juan
Specifically, I'm looking for things that get the blood moving, but as fingerpainting shows the fun factor is foremost. Here's what I have so far, I would like some more suggestions. Oh, and the lighter on the wallet the better. Think $10/wk allowance 
Mini Golf - It's fun! Lots of chances to goof around.
Tag - Can be played anywhere. It encourages touching, and it makes me happy to run around.
Time capsule - Bring a shovel and a container of some sort, then bury things and write a note talking about them. (lots of fun if personal things (panties) are buried with a story explaining them.
Basketball - It's active, sweaty, and I'm bad at it (so there will be plenty of laughing)
Fingerpainting! - I haven't done this in forever and it was so much fun! Some trash clothes, some fingerpaints, and a drop cloth or something for easy cleanup.
Jello Wrestling - Not many chances to do this. You need a kiddy pool and a whole crapton of jello, but it's really fun and sexy.
Build a clubhouse - Not to use, just to build. I remember a lot of attempts to do this as a kid. We just used whatever we could find, and so should you. Don't buy nails or wood, look for shopping carts and bring some sheets and clothing clips. After it's built, you should practice smooching in it (y'know, to make sure it works.).
Spar - I havn't had anyone to spar with in forever. It's hard to find a proper artist to spar with though.
Photo Booth - A classic Mall photo booth. Goofy pictures.
Clothes shopping - a strange thing for a guy, but I don't mind playing dress up every now and again. I over exaggerate things and play it up.
Rock Climbing - Either a rock gym or boulder climbing. Freefall is fun!
Play dirty cops - Like cops and robbers, only you're both cops, and one of you's dirty. Try to arrest each other. Whoever gets arrested is the dirty one.
Biking - Go ride bikes. Look for new places, get lost. (Going for a drive is a good substitute, but it doesn't get the blood moving.)
Race - Just a straight out sprint. Running is fun, and it gets you tired. Which is also fun.
Mini Golf - It's fun! Lots of chances to goof around.
Tag - Can be played anywhere. It encourages touching, and it makes me happy to run around.
Time capsule - Bring a shovel and a container of some sort, then bury things and write a note talking about them. (lots of fun if personal things (panties) are buried with a story explaining them.
Basketball - It's active, sweaty, and I'm bad at it (so there will be plenty of laughing)
Fingerpainting! - I haven't done this in forever and it was so much fun! Some trash clothes, some fingerpaints, and a drop cloth or something for easy cleanup.
Jello Wrestling - Not many chances to do this. You need a kiddy pool and a whole crapton of jello, but it's really fun and sexy.
Build a clubhouse - Not to use, just to build. I remember a lot of attempts to do this as a kid. We just used whatever we could find, and so should you. Don't buy nails or wood, look for shopping carts and bring some sheets and clothing clips. After it's built, you should practice smooching in it (y'know, to make sure it works.).
Spar - I havn't had anyone to spar with in forever. It's hard to find a proper artist to spar with though.
Photo Booth - A classic Mall photo booth. Goofy pictures.
Clothes shopping - a strange thing for a guy, but I don't mind playing dress up every now and again. I over exaggerate things and play it up.
Rock Climbing - Either a rock gym or boulder climbing. Freefall is fun!
Play dirty cops - Like cops and robbers, only you're both cops, and one of you's dirty. Try to arrest each other. Whoever gets arrested is the dirty one.
Biking - Go ride bikes. Look for new places, get lost. (Going for a drive is a good substitute, but it doesn't get the blood moving.)
Race - Just a straight out sprint. Running is fun, and it gets you tired. Which is also fun.