If you were actually interested in the content, there are countless ways to open a PDF safely.

* Open the PDF in a non-adobe reader such as Foxit and Sumatra w/ JavaScript disabled

* Both FF and Chromes internal PDF viewers ignore JS

* You can preview a PDF in Google drive

* Open the PDF in a sandboxed VM.

Guessing for your history of spammming 1 line pointless comments, you probably already know this.