Douchewaffle is excellent as an insult. "Douche" gives you the idea of assholish shitbagginess, and "waffle" gives you a double-whammy: wishy-washy flip-floppiness on the one hand and then there's just the silliness of the word on the other. So you're calling someone an wishy-washy assholish shitbag with a silly sounding name in one convenient word! Brilliant!