Ooby Dooby shows up as a 50s song in the Rock Band Blitz store but once purchased, it sorts as 1987 because it is a rerecord. I bought it expressly to get the play a song every decade achievement. Once I purchased Walk the Line by Johnny Cash, the achievement popped. This thread is a warning for achievement enthusiasts. Also, how do I get a refund? :P (I'm serious.)
EDIT: Hmm, just saw the other thread about this, but the thread starter had to go and make a dramatic statement instead of getting right to the point.