What happens when you make an illuminati sign?

You show the world what a delusional glommer-onner you are. Two problems here:

1. The only sign associated with the Illuminati was the Owl of Minerva. And, no one alive today really knows the significance of it.
2. And, the Illuminati has not existed since 1785.

You might just as well tattoo yourself with the glyph that was alleged to have warded off werewolves. Perhaps you could copy the television show Supernatural and have your ribcage etched with the same Enochian signs that ward off and shield Sam and Dean Winchester from demons and angels.

Or, perhaps you could step over to the realside of reality and recognize that flipping any sign is ludicrous at best, and potentially dangerous (from other humans not the occult or some mythical organization) due primarily to misinterpretations from gangbangers or Cartel members, provided you are in the wrong place at the wrong time when you do something so inane.