If you need to draw Scribble Lines in PowerPoint 2010 then you can use the scribe tool that is one of the shapes available from the Shapes menu. The following article will show you how to use the scribble tool to draw a simple scribble line or figure.
To start using this tool go to Insert -> Shapes option and then look for Scribble tool under Lines section.
Then, you are ready to press your left button of your mouse and start drawing the scribble line. Notice that you can create different figures and lines, and you can then configure the shape properties for example to add an arrow head to the line shape like in the last example below.
In powerpoint 2010 we can now apply the concepts above to draw a scribble line, but if you have another version of powerpoint like powerpoint 2007 or powerpoint 2013 then you can use the same approach to draw scribble lines for your powerpoint presentations.