I too had to google it. Fun!! For those that are curious here is one link of many hits I got. Basically it is Finnish descendents answer to St. Patrick. LOL
http://www.sainturho.com/
I am surprised I didn't know of it. My mom was born in Finland. Although she was of French/Russian descent and moved to Sweden early on in her life. It seems the tradition originated in the US so maybe that is why she never told of it.