It was just diet coke in a glass with ice. I thought that since I flew up the stairs and got it in the water right away that it would just rinse out but it didn't. Of course the back is white with pastel polka dots so it shows really well. It kind of sprayed across half the quilt! I did put a little laundry soap in the washer perhaps that set the stain? I am going up right now to see if I have any Oxy clean . I just want to scream.