Slinkman even says in "Edward's Big Bag", "Kidney Beans, front and center!"
Not only that, but the Jelly Trio's name. Now, bear in mind that jelly beans are very different from the average bean, which just goes to show that Lazlo, Clam and Raj aren't like other Bean Scouts.
In "Beans and Pranks" after Lumpus wakes up and thinks the Jelly Bean scouts have made his face ugly with a prank he goes furious into the cafeteria. He complains about his face and most of the scouts clearly express their fear of Lumpus' face, but then it turns out his face was alright. So why would the scouts be afraid? Simple, Lumpus was angry and him frowning did make his face look scary.
In Boxing Edward, after finding out that Dave sends letters to his grandma (and needing the stamps anyway to mail himself out of camp), Edward tricks him into giving him all his stamps by going into this sob story about how Dave's grandma's eyesight is probably not what it used to be and she probably won't be able to read his letters anyway. Dave then declares he'll never send letters to his grandma again. That's gonna have some dire consequences.
Unless Ping-Pong or any other family members tell him that her eyesight is fine anyway.