Joe -- I feel your pain, buddy! I had a similar situation. Some friends came up during foliage season a few years back and after three days of eating everything and watching us work, I handed them a grocery list (no $$$) and posted a list of chores that needed doing. Thankfully they took the hint. Not only did they get groceries, but they did all the cooking and cleaning in the house. Even helped split firewood and mowed the lawn!
Might not work for everyone, but in this case giving them a clear set of expectations and providing them with a visual list of the chores they were interfering with prompted them to ante up and cemented our friendship.
Good luck! Pete