Drummies! are a type of chicken drumsticks that Greg implies are the best chicken drumsticks he ever ate, but doesn't say their name when ordering them for fear of looking ridiculous. Later on, he finds them in a grocery store while shopping with Susan, and realized that they are cheaper than the ones at holiday bazaar, thus knowing they were ripping him off. As a result, he bought many of them, so he would win it from the school and start his own holiday bazaar with his friend Rowley, which didn't actually happen.
In real life, Drummies are a name of homemade chicken drumsticks.
They also appear in the online book when Greg goes to church bingo with his Gramma and goes to the food counter to order them, but he sees Piper Matthews (Holly Hills' online counterpart) behind him in the line, so he decides to order meatball sub instead because he didn't wanted to look stupid while ordering them in front of Piper.