You actually gotta triple backslash.

Enclosing any text between _s tells markdown rendering that you want it to be italicized. Putting a \ behind a markdown character tells the renderer to _ignore that,_ and render the character as normal.

¯_(ツ)_/¯

But \ is a markdown character, so when you double backslash, the first \ tells the renderer to ignore the second \, and the _s act as normal, italicizing the face.

¯\(ツ)/¯

So you gotta triple backslash. The first \ tells the renderer to ignore the second \, and the third \ tells the renderer to ignore the _

¯\_(ツ)_/¯