We often give the kids a dessert after dinner if they try everything on their plate. It can be anything from a popsicle to a cookie, but they love a little something sweet no matter what it is. One day I had a Hershey bar that I was planning on having them split after dinner. This conversation happened while they were eating dinner before dessert time.
Me: "Remember, if you do a good job on your dinner I have a special treat for you!"
For some reason "special treat" really gets my kids going. Maybe it's the novelty of not knowing what the treat is. Regardless, if I mention a special treat I can usually get them to eat a few more bites of veggies and such.
Sam: "Ohhhh, what is it?"
Me: "Can't tell you or it wouldn't be a surprise. Eat one more bite of broccoli and you can have it."
Sam: "Ok, I ate it! Now what is the surprise?"
Me: "Ok buddy, here it is!" (while showing him the Hershey bar)
Sam: "Oh Mommy ... chocolate makes me smile!"
And here's the blissful look of chocolate anticipation ...