emerald necklace
Just like a pearl necklace, except when the guy has an infection or STD, making his spooge a greenish color.
"Dude, I got to get to the doctor cuz I was trying to give this bitch a pearl necklace for her birthday, but it came out as an emerald necklace instead. I shouldn't have went to that Thai hooker on my business trip last month... she must have given me gonhorrea."