It's yearbook time. Melinda isn't sure what drives people to collect signatures from people they don't even really know.
The cheerleaders are actually competing to see who can get the most signatures.
Now, Melinda understands why Todd Ryder is popular with the popular people, even though he's "Greasy, sleazy, foul-mouthed, and unwashed" (79.4). See, Todd is the official photographer for the yearbook. People who are nice to him get good pictures in the yearbook. People who are not, like Melinda, might find an unflattering picture of themselves in the yearbook.