Available from now until April 3rd, there's a new Call of Duty: WW2 expansion themed around St. Patrick's Day, and it comes with a tiny speedy evil undead leprechaun. Nothing like tasteful celebrations of heritage.
There's a Leprechaun Hunt Mosh Pit competitive multiplayer playlist, and when playing it, you'll occasionally see a tiny green-clad undead creature run past with a cackle of laughter. He's pretty darn hardy, but if you manage to kill him, you'll immediately earn all three of your score streaks. The image up top of the dead leprechaun is from Reddit user Double_08, who managed to kill one early in the event.
Players seem pretty intent on leprechaun hunting once he spawns, so it's up to you if you go for the green blighter too, or focus on killing off people running around staring at the floor.
Also, the Operation: Shamrock & Awe community event adds in a bunch of green optional colour variants, as well as putting in some rainbows and pots of gold to spruce up the place.
You can experience all these Ireland-themed CoD experiences for roughly three weeks.