In every family, there’s generally at least one prankster. He loves to put Vaseline on a doorknob, saran wrap your car, or sneak the occasional whoopee cushion under your chair. And while it’s not always fun to be on the receiving end, we must admit, we’ve pulled a few jokes on people and enjoyed the laughs that ensued. As it turns out, helping others play jokes on friends and family can be a pretty lucrative business: In fact, Joel Comm, the developer of the iFart application for the iPhone and iPod Touch,