Use the Pen tool to draw the rough shape. Tweak the shape with the 'Direct Selection tool'(expand the 'Path Selection tool' located above the Pen tool) and the 'Convert Point tool'(located in the expanded Pen tools)
To expand a tool(Toolbox) see if there is a little triangular arrow(bottom right), click and Hold to expand.
Once you are happy with the shape you can transform it to the desired size, and then either 'select' the shape (CTRL click the thumbnail in the layers palette, or right click the shape and 'Rasterize' it(convert to raster/Bitmap).
Moe: It could have been a real ugly situation, but luckily I managed to shoot him in the spine.