Lime Rime, Leery Ed

Look at the frosty rim of my shot glass:
It's just a little green, since this old lime
Was sitting there for several hours, and slime
Formed on the edge. I should have let it pass,
But when the barman said, "All flesh is grass,"
I started worrying. Is that a crime?
He's made these cocktails for the longest time,
But now he sounded way too full of sass.

"Don't sweat it," he insisted. "Come on, Ed,
What do you see? There isn't any hair,
Or other crap like that. No germs, I swear."
But then he smiled. Though I heard what he said,
I saw that frosty rim, and I saw red,
And thought about what might be lurking there.