- 1. Predominantly green cels or images
2. Cels/sketches with leprechauns, shamrocks, or pots of gold with rainbows
3. Cels/sketches with Irish-style music/dancing/overindulging

This is Katabami aka "Wood Sorrel" aka Oxalis corniculata from Episode 35A of Powerpuff Girls Z. He's getting hammered (like a good Irishman on St. Paddy's Day) by Buttercup for being a dangerous weed monster. Actually, he's just a misunderstood wild plant, and his close relative Oxalis triangularis is what you see in stores this time of year being sold as "shamrocks."
Irrelevant note: what St. Patrick picked on Tara Hill as he explained the Trinity to the assembled chieftains was almost certainly Trifolium repens, a type of clover. But the Oxalis species arguably make a nicer triple leaf. And the katabami is, also appropriately, one of the oldest crests of Japanese martial arts clans, making it a perfect St. Patrick's day image for Anime-Beta.