Blue, particularly dark blues. Or like, a dark purple/raisin color. I'm talking that dark reddish purple that almost looks like a bruise. And shimmer is a must.
I'm not particularly into people messing with my feet but I am really excited by acts of servitude, and one such act would be having Monkey paint my toenails for me. If he fucks up, he gets spanks. Or, ya know, kicked.