Just a note, I live in the WC and am a Stormers supporter myself. I've just found that boo'ing is a lot more common where Stormers fans are involved.
Last night during the Stormers game I could actually hear the booing on the TV from the Stormers fans when the opposition got a penalty kick.
And to whoever said good sportmanship must only come from the team, not the supporters, you're really deluded. Supporters are just as important, if not more so, as the team itself. Without supporters there wouldn't be rugby to watch.