Here are the comparative and superlative forms of the adjectives:
* Fat - fatter - the fattest * Merry - merrier - the merriest * Many - more - the most * Bad - worse - the worst * Successful - more successful - the most successful * Thin - thinner - the thinnest * Simple - simpler - the simplest * Dirty - dirtier - the dirtiest * Wide - wider - the widest * Dry - drier - the driest