One Way or Another by Blondie
This one is by no means a cakewalk. The verses have lots of rapid note changes, and the "I'll getcha, i'll getcha" and "I'm gonna trick ya, i'll trick ya" have pitches that can be hard to identify. But for me, the icing on the cake is that the song gives very little room to breathe in most areas.
Most people claim this the hardest FC in the game, but I have to respectfully disagree and say that goes to L'via L'viaquez. I'd also much, much, much rather take this one over the Rock Band 2 chart with the broken talkie any day of the week. If you're gonna try to tell me otherwise on either of those opinions, fuck off. If you disagree, that's perfectly fine, but I don't want to hear it.
Also, please excuse me pausing mid-song. I wasn't resting, I thought I heard someone downstairs calling me. I have FC'd the song without pausing before, so again, please don't act like it's a big deal.
Either way, hope this helps some of you who might be struggling with it.