Dip the tip of each lollipop stick into the melted peanut butter, and carefully insert a stick into the bottom center of each brownie pop. (Be careful not to push through the top.) Now, submerge each pop completely into the peanut butter coating, lift it out, and hold it upside down over the bowl to allow the excess frosting to drip off. Then, stick the lollipop stick into a piece of Styrofoam to hold the cake pop upright. (You can also lay it on a piece of parchment paper, but you will end up with one flatter side.) Repeat for each pop.