Robbie the Ribbiter is a unisex, slightly slouchy, crochet beanie pattern for a red-eye tree frog. One size fits most adults. US Crochet terms. Made with 6 colors of worsted weight yarn, a size 5mm and 6mm crochet hook. Knowledge of crochet graph patterns and basic crochet terminology needed. Additionally, you need to know how to make a center-single crochet stitch (AKA waistcoat or knit stitch) and how to do decreases of this stitch.