They are referring to the green wall of ivy that borders the outfield at Fenway Park, where the Boston Red Sox play. It's a famous (and old) baseball stadium.
i just started watching The Guild on youtube... hiding in my room incase someone should discover my nerdyness.... i'm glad to see i'm not alone...
and me and my lvl 72 troll priest thank you from the bottom of our little hearts...
(p.s. you should talk with Blizzard)
