Back when I was an elementary school student in Hinton, USA they would do a Bedlam blood drive thing every year — it, I think, is my earliest memory of the rivalry.
They weren’t harvesting blood from elementary school kids (that seems illegal). Instead, you paid a quarter and got to pick whether you wanted to put a paper OSU helmet on the wall or a paper OU helmet. As is the case in most places in the state, the OSU supporters were outnumbered, but we’d skip trips to the pop machines and use all of our quarters to fill the OSU side up.