"Fine", "Nothing" and "The HEAVY SIGH" are warning signs for sure. A good man will learn to leave the room or become extremely considerate at that point. When you return to the room, make sure you have just carried out the trash or you are about to go into the barn for a long time.
For me, it is "Dont sit there and watch me work." If I am ironing, then don't sit and watch me unless you are planning on taking up the sport yourself, very quickly. When I get out the ironing board, Steve knows to leave the house for an hour.
"Stay out of my garden" is another. Steve has a brown thumb and plants will die if he passes. He is the black death for plants.
And finally, "Stay out of my kitchen". You aren't helping and if you eat one more piece of squash you will draw back a nub.