Actually, licking it is your best option. Your saliva will break it down and the antibodies in the saliva will protect you from getting ill. Your toungue is soft and will not cause swirls as long as you lick in a back and forth motion, not circular. And obviously if you are sporting a toungue ring, remove it first. This is what I do when I get bird droppings on my car. Good luck!

Oh I almost forgot. You could just wash it with soap and water since that's how you wash your hands after you drop a deuce, assuming you wash up after.