-EDIT- FOUND IT NVM

For new players of Subeta this is not so obvious, so I am answering this anyways. You can chuck snowballs at other users for fun and Achievement. They will briefly show up on your target's HA in various fun-shaped snowball splats. There is an igloo-shaped building in Arctic Frost to buy the snowballs. You can't throw them yourself. In the lower left corner of Arctic Frost is the Snowtapult that does the flinging for you. I'm not sure if the fansite Suibetalodge has the images of what each snowball looks like when it hits, or if you have to dig through the Forums here to see if anyone has done a thread about it.