I was afraid to follow Philster’s (undoubtably very helpful) links, but I can tell you, from personal experience
Bright purple sugar cookie frosting=Very green waste material
so it doesn’t always have to be that you ate something green. Although, as the case of my cousin’s toddler once showed several of us, green Play-Doh will do as well.
Basically, bile is green and dead blood cells are brown. If your poo is speeding through your system very fast (possibly because of big overeating the past weekend?) it is possible to have naturally green poo.
There’s a lso a list in that article about other things that can cause green poo.
The blue food coloring in things like powerade reacts with bile and produces a bright green color. The frosting mentioned above contains the dye, as well as grape drinks.
Clearly your body has joined the environmental movement. The news is all over making your life green. Apparently your body has taken this to heart, or in this case, to shit.
I can’t think of anything purple or blue that I ate. The only thing unusual is that I went for 2 months without drinking any alcohol, then I had a fair amount of beer over Thanksgiving weekend. In addition to that it’s been basically poor eating habits during that time, with 2 meals consisting of burgers and fries (one of them had bleu cheese, tho).
I think large enough amounts of any artificial color will have that effect. Well, from experience, a lot of red Jell-o will have more of a reddening effect, but you get the idea. Licorice does the job for me.
Quite possible the beer reacted funny with the rest of your diet.