My kids know when I am about to lose it. I start sighing. Loudly. I tend to lose it at the end of the day . . . usually on the occasions when I discover a MESS of epic proportions, which I now have to deal with after many hours of writing and assorted stress.
Demon Baby now predicates messes with coming in to me and saying the following:
"Mom . . . nothing broke. But . . . [FILL IN "I spilled an entire half-gallon of orange juice on the floor" or "I let the senile dog into the family room and he peed in there," or "I got creative with my food again" or "You might not want to look at the couch"]."
Then I usually sigh and slap my pen down on my desk.
Then, lately, he usually pats my arm and says, very slowly and patronizingly, "Now Mom, stop freaking out and CALM DOWN [aside, spoken as if I am a jumper on top of the George Washington Bridge] . . . you don't want your blood pressure to go up now, do you?"
And usually . . . that's enough for me to remember that life is too short to care about messes.