Be Prepared - Dress the Part
Be aware that any metal detected at the checkpoint must be identified. If you set off the alarm, you will be required to undergo a secondary screening, including a hand-wanding and a pat-down inspection.
You can remove metal items at the security checkpoint and place them in the bins provided. The bins will be sent through the X-ray machine. You can save time, however, by not wearing metal items or by placing such items in your carry-on baggage before you get in line.
TIP: Avoid wearing clothing, jewelry, or other accessories that contain metal when traveling.
Hidden items such as body piercings may result in a pat-down inspection. You may ask to remove your body piercing in private as an alternative to the pat-down search.
TIP: Avoid placing metal items in your pockets.
TIP: Instead, place jewelry and other metal items in your carry-on baggage until you clear security.
TIP: Pack your outer coat or jacket in your baggage when possible.
Outer coats including trench coats, ski jackets, leather jackets, overcoats and parkas must go through the X-ray machine for inspection. If you choose to wear an outer coat to the checkpoint, you will need to either place it in your carry-on or put it in the bin that is provided for you. You will not need to remove suit jackets or blazers unless requested by the screener.
http://www.tsa.gov/public/interapp/editorial/editorial_0076.xml