Dipping a flag is when you tilt a flag downward in front of a person or thing as a sign of respect. The U.S. Flag Code states that the American flag should never be dipped. American flag buntings are available to be used as patriotic decorations instead. Displaying the flag respectfully on a flagpole is not considered decorative and is acceptable to do. For example, you should never use the American flag as a tablecloth or drape it over a podium that someone will be speaking at. There is a debate over whether this includes wearing clothing like shirts and dresses with the American flag on it. Some people view it as patriotic, others view it as offensive. The only exception to the rule is for military members, police officers, and firefighters, who are all able to wear an American flag patch on their uniforms. This includes writing words on the flag, drawing numbers or symbols, or attaching any kind of image to the flag. People in uniform, members of the armed services, and veterans do the military salute. While it is customary for non-military and non-uniformed persons to remove any headwear and hold their right hand over their heart, the US Supreme Court determined (in their ruling West Virginia State Board of Education v. Barnette) “If there is any fixed star in our constitutional constellation it is that no official, high or petty, can prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion or force citizens to confess by word or act their faith therein.”

Summary:
Never dip the American flag. Avoid using the American flag for decorative purposes. Don't use the American flag as part of a costume or uniform. Never draw on or mark the American flag in any way. Salute the flag properly.