What cultural faux pas should I try to avoid making in Washington DC?

"It is important to be respectful of the local culture when visiting Washington DC. It is important to be aware of the local customs and to be mindful of the language you use. Avoid making jokes or comments that could be seen as offensive or disrespectful to the local population. Additionally, it is important to be aware of the local dress code and to dress appropriately for the occasion. It is also important to be aware of the local laws and to follow them. Finally, it is important to be respectful of the local environment and to be mindful of the impact your actions may have on the local environment," mentioned another expat when asked about moving to Washington DC, the United States.