You can use this tool to generate striket̶h̶r̶o̶u̶g̶h̶ text and copy & paste to Facebook & Twitter
On this page you can generate struck-through, cross-hatched, underlined, waved
or ... While Facebook allows you to make text bold or italic, there is no way to
write ... are still plain text, which you can post on Facebook, Twitter, Google+ etc.