Curtis Sliwa hopped into the water off Coney Island on Sunday, defying Mayor Bill de Blasios no-swimming order and mocking hapless city Parks Department cops who watched him from shore as a crowd cheered him on. But Sliwa, dressed in a wet suit and his trademark red Guardian Angels beret strolled into the surf and swam around for about an hour without consequence, while a crowd of people on a pier near the old Parachute Jump cheered for him.