But we cannot forget that Luffy thinks a glop of Magellan's poison is poop at first. I'm sure that'll affect the color and why I made my prediction (I'm going to re-post it since we're getting close to the confirmation) and yes, I'm convinced that'll be a cheezy CGI effect.
! http://img.photobucket.com/albums/v232/Conekiller/MagellanPoison.jpg
Holy crap I love the swirly pattern thing going on. _