Artwork and photographs can tell stories in ways that no amount of words can, and Clipart does basically the same thing. The right picture can enable readers or viewers to visualize what the writer is describing. Using Clipart beside text will make a few descriptive lines come alive.
And then your friend finds out. Will he be a little bit hurt? Maybe. He might claim that this is his first time being late, that he won't ever be late again-well, that's not such a big deal. You don't have to argue it with him. Just explain. Tell him you're not crediting the clip art to him, so it won't sully his reputation (and if you have done your work right, the free graphics you've got are good enough that he shouldn't worry). Tell him you're just waiting and that you needed something in place. If he's really concerned about his art, it might speed him up; if he isn't it might slow him down. In either case, with your free clipart, you're set. You can let things run themselves and go join your buddy on the couch for potato chips and movies. After all, he might not start working on your project any time soon.
So before you download clipart off the internet, you need to determine what kind you need. For the classroom and basic computer programs such as Word, you most likely just need to get royalty-free raster clipart. If you need to use a high tech computer and software with a vinyl cutter, laser, or CNC then you need a vector clipart graphic. Either way you should use royalty-free clipart to be legal for commercial and other activities.