A rarely traveled spot in the deep woods, some large canvas sacks, rope, lime, a shovel and some peppermint candies.
Dig a hole in the woods, fill the canvas bags with dirt. Tie them off with ropes with an easy to open knot. When they start bickering, throw peppermint candies at them to get attention. When they stop, inform them that their cars will be filled with forest dirt if they keep it up. Put the lime on your corona, sit back and enjoy a much happier game.
If you find you have to kill them anyway, well, at least you have everything you need, but the wrong kind of lime.