Combine the flour and water and mix until creamy. More or less water may be added to obtain the desired consistency.
The mixture may be brought to a boil (stir!) to make a more durable and thicker paste (or maybe a tasteless gravy?).
Tips:
Don't dump this in the sink or toilet without mixing in a LOT of water first... otherwise a clog may result!
Dried areas will clean more easily if soaked with water first.