Picnic dinner! That sounds fun. On my imaginary picnic dinner menu:
Finger sandwiches
You can put whatever you want in them, but I typically go with something different than normal sandwich combos.
Try cucumber, mint, tomato, and mozzarella. Or, bell pepper, basil, bree, and balsamic vinegar.
Gazpacho! (if you have plastic bowls)
Now this is my secret recipe, so don't go posting it all over the internet!

Get your blender out.
Throw in a tomato, bell pepper, cucumber, mango, mint, a touch of onion and garlic, salt/pepper to taste, and a decent squeeze of a lemon.
I am assuming there is no grill, if you have access to a grill make:
Barbie Shrimp Poppers
Shrimp
Bacon
Cream cheese
Jalapenos
Chop jalapenos and mix into the cream cheese. Slice the shrimp down the belly and open slightly. Stuff the delicious hot cheese in there. Wrap in bacon. Fasten with toothpick. Throw it on the barbie. Salivate while waiting.