"Challenge accepted".
Replacing Social Security with personal accounts, either for everyone or for those who choose to opt out.
Ending drug prohibition.
Recognizing WW2 is over, and ending personal income tax withholding.
Recognizing WW2 is over, and bringing the troops home from Europe.
Recognizing the Korean War is over (all but the inevitable collapse of North Korea), and bringing the troops home from Korea.
Officially declaring war every time our military personnel are put in harm's way in a distant place.
Requiring all laws go through the Congress in the manner described by the Constitution, even the ones written in regulatory agencies that aren't called "laws".
Recognizing that treating something as interstate commerce when there is no commerce or there is no transaction between parties in different states is dishonest, and a violation of their oaths of office.
Recognizing that propping up the governments of other countries because they are "allies" (Allies? In peacetime?) is a terrible idea.
Recognizing that attempting to topple the governments of other countries because they are enemies of our "allies" (Allies? In peacetime?) is a terrible idea.
Realizing that training and arming insurgents in support of our "allies" now may create new enemies for the US in the future. (Alex, "Who is Osama bin Laden?")
Did I miss any?