Americans celebrate the holiday by wearing green clothing. Many people, regardless of ethnic background, wear green-colored clothing and items. Traditionally, those who are caught not wearing green are pinched.
http://en.wikipedia.org/wiki/Saint_Patrick's_Day

You know, make him lie still on the table while we get drunk around tell embarrassing stories about him all night.

http://www.kcirishparade.com/Events/westport_run.htm

Don't forget the pot-a-toes!

Many parades are held to celebrate the holiday including the cities listed below: The longest-running Saint Patrick's Day celebrations in the U.S. are: Boston, Massachusetts, since 1737 New York City, since 1762 (247th Consecutive Parade in 2008) Philadelphia, Pennsylvania, since 1771 Morristown, New Jersey, since 1780 New Orleans, Louisiana, since 1809 Buffalo, New York, since 1811 Savannah, Georgia, since 1813 Carbondale, Pennsylvania, since 1833 Milwaukee, Wisconsin, since 1843 Chicago, Illinois, since 1843 New Haven, Connecticut, since 1845 Saint Paul, Minnesota, since 1851 San Francisco, California, since 1852 Scranton, Pennsylvania, since 1862 Cleveland, Ohio, since 1867 Pittsburgh, Pennsylvania, since 1869 Kansas City, Missouri, since 1873 Butte, Montana, since 1882 Rolla, Missouri, since 1908 Holyoke, Massachusetts, since 1951 Baltimore, since 1956 Denver, Colorado, since 1962 Las Vegas, Nevada since 1966
http://www.st-patricks-day.com/st_patricks_day_parades_home.asp