You can block HTTPS in Transparent mode, but you need to install a pfSense server certificate on every client that will use the proxy, which is a massive pain in the ass.
haha i love that "pain in the ass" so true ;D
Also @sjain WPAD will work but there's some androids that wont work. As chris4916 pointed out to me that you would need Drony to install on the androids, which may not work in your situation. Tell you truth if you don't mind just showing a blank error page on block sites use pfBlockerNG it gets the job done maybe not as neat but usually people enter www.facebook.com it comes up at HTTP (which squidGuard will show the nice blocked page) but if they Google search Facebook it comes up at HTTPS pfBlockerNG will not let it connect.