It's ok to eat chips. It's ok to eat chocolate bars. It's OK to enjoy life and treat yourself with "fun" foods. Just BE SMART about it. Eat it in moderation. And make sure when you're eating your meals for the day you're eating balanced, nutritious, well-portioned meals. Then, enjoy fun foods every now and again.
It's not what you do, but how you do it. Learn to eat a few handful of chips instead of the whole bag. Eat half a chocolate bar and save the other half for another day. Your body can handle these kinds of foods if most of the time you take good care of it.
Life is for enjoying. So please enjoy! And stop stressing over things like this.
Have a tough time stopping at couple handful of chips? Can't help but finish a huge chocolate bar once you get started? No problem. Just carry a mini travel-size mouthwash (or toothpaste) in your bag. Or just have it handy in the car.
When you have the urge to eat "fun" foods but trying not to, or when you can't help but want to eat more than a few, just rinse your mouth or brush your teeth. This can help dull your taste buds, and chances are, you'll lose your appetite for that moment since the food won't taste so great.