Yes or No?

So I've been reading this parenting book by John Rosemond. One of the ideas that stuck with me is "let your yes be yes and your no be no". This will drastically reduce whining, cajoling, and begging from your kids. Now in my brain this sounds good. In reality, I fail to live up to this advice - daily. Yesterday, I had an opportunity to see the principle at work with one of my kids. It was dinner time and M. didn't think she would like what I made. She asked if she could make a sandwich to go along with it. Unthinking... I responded like this:

• Mom: You know, I bought the sandwich stuff for your lunches this week.
• Kid: Well, there is plenty of bread. Can I just make a sandwich for me?
  
• Mom: I'd rather you not.
• Kid: Would you just tell me yes or no? I don't know what you want me to do.
• Mom: (still reasoning and explaining...) I was hoping you were mature enough to figure it out.
• Mom: (coming to her senses...) Oh, the answer is no. Eat the food I made for dinner!

Hooray, God showed me with a very clear example - directly from my own kid's mouth, that they really want clear, concise answers. Let yes=yes and no=no. Keep feelings and hints out of the situation.