Vasta or vihta. Basically the same thing, just difference of dialects. Vihta in west, vasta in east.

Traditionally eating or drinking in sauna is forbidden (and could make the Sauna Gnome angry). Drinking beer in sauna has become very common now though, but eating is still kind of a niche, but I guess it comes from using the heat especially in the wood fire stoves to cook food on the fire to regain some energy when you leave the sauna to have on the porch but not inside the sauna. Also the birch branch vihta/vasta is many times incorrectly said to just help with blood circulation or such, but the sap that comes out of the leaves acts like a soap, and also have a nice smell so like a cologne as well. They are mostly used for midsummer day celebration (when they are fresh and plentiful) and there are certain rituals connected to that, and not so much for Christmas sauna but have been used in association to cleansing and other rites.

Sauna is king ! No way i can live without a sauna and after sauna swim now.