I'm not sure what the craziest is... there's 3 or 4 things... I guess since I'm young my sense of things can be broadened to stuff in which people with families can not really do.
Quitting my job and hiking the Appalachian Trail, takes 5 - 7 months if you do the whole thing in one shot.
Kayaking the Maine Island trail, it's 375 miles worth of water that has 188 islands that are uninhabited.
I guess #4 would be dropping everything and just moving to a new country and trying to find a job and live somewhere differently