Handshake or Fistbump?

http://en.wikipedia.org/wiki/Fist_bump
http://www.theatlantic.com/health/archive/2013/11/the-fist-bump-manifesto/280175/
http://www.ryot.org/study-fist-bumping-could-save-your-life-seriously/480285
http://www.spitfireglobal.com/fist-pump/
http://www.sodahead.com/fun/fist-pumps-or-handshakes/question-3926281/?link=ibaf&q=&imgurl=http://images.sodahead.com/polls/003926281/fist-pump-119116086354_xlarge.png
http://answers.yahoo.com/question/index?qid=20100721174939AAHF38q