A pen (Male, Any)

... a ballpoint pen.

"Here" she says "Whatever you write with this pen will become the truth, no matter how ludicrous. Want to change the world. This'll let you do it. Of course it'll run out of ink eventually but until then you'll be a God. Won't work on me, of course. I'm not an idiot. Now git. I've got things need doing."

You walk off bewildered holding the pen.

You find yourself at the bus stop before it occurs to you to test whether the old lady was lying or not. You pull out a book of note paper and write ...