Weapon of choice

When I eat my dinner at the computer, which is about once or twice per week, the cats come a runnin. They used to sit patiently next to me and I would usually save a little piece of meet and leave it for them when I was done. In their old age they have started acting much like they did when they were babies, by grabbing for the food as I'm lifting the utensil to my mouth. There are only 2 things I can do to get rid of them, one is to whistle for the dog but since I'm not good at whistling they have figured out that the dog won't respond and so they stay. The other one is the air duster:




They FRRREAK OUT at the sight of the duster. I don't even point it at them anymore, I just sit it next to my plate and they sit about 2 feet away and scrunch up their faces just in case I grab it and point it at them. I feel guilty but I ate peacefully tonight.