Nero snorts coke, drinks martinis, and usurps the crown of the Roman Emperor Claudius, spurred on by his scheming mother, Agrippina, who puts Erica Kane to shame. Meanwhile, the virginal Poppea promises herself to every male in sight. To confuse matters more, there are two countertenors and a woman playing a man! Can you believe it? Agrippina is a comedy by Messiah Man George Frederic Handel, and it’s the latest rethinking of baroque opera by Chicago Opera Theatre. The music is glorious (played on period instruments), the cast is young and attractive. Athenaeum Theatre through May 10; (312) 704-8414; $35-$75.