a)Why the hell do you own a dog?
b)Why the hell are you at the dog park?
In a dog park, there are generally lots of, you know, DOGS; these animals tend to be very friendly and will approach you with their tails wagging and tongues lolling, trying to get close to you so you can dispense pats and behind-the-ear scritches. They won't understand why you so very brusquely push them away, and it might make them even more persistent. If you feel that uncomfortable being around these creatures, go home. Before I'm forced to kick your ass because you hurt my beloved puppehs' feelings.
And this may be very mean...if you have SEVERE acne covering your entire torso, please, for all that's holy, KEEP YOUR SHIRT ON.