Thirded! I've always loved "cum for me" because it's a command and worked well with orgasm control training because I felt like I was obeying him and the whole 'responding to a trigger' seemed like a sort of side effect when in fact it was his carefully crafted sinister Master plan! It makes cumming SO much more emotionally fulfilling for me too, because of the whole obeying/orgasms are his, aspect, too.