So I was looking at my last.fm profile and after the Arcade Fire Neon Bible tour gig in Glasgow was mentioned in another thread I spotted a review of said gig. Whilst commenting on Patrick Wolf's support slot I clearly didn't know what a theremin was and described it thus,

"one of those cool things Bill Bailey always plays that you put you're hand over and it makes noises"

How would you describe other instruments if you were ignorant of their name?