There's a big fat Grey Squirrel that's been poaching out of our compost bin lately. She has to run right across our front lawn to get her rotten veggie bounty. So the dogs get a fantastic view of her bouncing fluffiness from our living room windows.
My dog, Martha, wants this squirrel so badly. I don't think I can explain to you how truly psychotic she becomes when she sees this thing out the window. She barks incessantly, shakes like a tweaker coming off a high, blows snot all over my windows, and blasts around the room, slamming into furniture, bouncing off the windows, trying to get a better vantage point every 3-5 seconds. And since Martha sneaks like an elephant, the squirrel hears all the commotion and just safely bounds away, knowing that the big scary dog is not so scary when she's stuck behind the big glass walls. The squirrel happily makes off with her coffee-ground-covered apple core to feed her family (and probably goes home to tell them that the stupid buffoon dog hit its face of the glass... again).