"Tick, you can't fight evil with a macaroni duck!" is from the hilarious animated series The Tick, specifically the especially hilarious episode Little Wooden Boy and the Belly of Love. One of the four or five plots of that episode was the rift that developed between Tick and Arthur over Carmelita and their friendship. Arthur had been spending more time with his girlfriend, Carmelita, and less with the Tick, and Tick felt like he was losing his sidekick. The tension building between them exploded into a confrontation on Craft Night, when Arthur tried to blow off the weekly routine of he and Tick making kindergartenish arts 'n' crafts for a date with Carmelita.
(The Tick brandishes a silhouette of a duck, made from pieces of macaroni glued to a sheet of paper.)
Tick: But Arthur, evil!
Arthur: Tick, you can't fight evil with a macaroni duck!
Tick: I'll be the judge of that!
(Arthur leaves.)
Arthur's date on Craft Night is the impetus for practically all of the episode's other events, including Tick's creation of Little Wooden Boy, and Tick and Arthur's encounters with the Swiss, Blowhole, and Carmelita's father, but those are all stories for another node...
(Ideally a node about Little Wooden Boy and the Belly of Love, but considering how long this explanation of one quote took and how much I like that episode, it would be quite an effort.)
I originally wrote this up because CrowJane asked where this phrase is from in her writeup, since deleted. Best to give credit where, uh, impetus came from.
...Two and a half months pass and I use the word impetus a second time in the same writeup.