Men At Work, the awesome 80s band from Australia, has been found guilty of plagiarizing "Kookaburra Sits in the Old Gum Tree." I'm not kidding.
From the Sydney Morning Herald:
Men at Work’s No.1 hit Down Under reproduced a “substantial part” of the children’s folk tune Kookaburra Sits In the Old Gum Tree , infringing copyright in the song, a Federal Court judge found today…Larrikin Music, which owns the copyright to the song Kookaburra , is now entitled to recover damages – potentially a huge sum – from band members and their record company….Larrikin alleged that the band’s famous flute riff came from the children’s tune, written in 1934 by school teacher Marion Sinclair.Via The Daily Swarm, who includes videos.
I find the similarity to be pretty minimal, a couple notes at best. In fact, there's really no need for a flute in this song at all. It's not like they ripped off the chorus.