"You can decide what we eat."
Translation:Du kan bestemme hva vi spiser.
The reflexive version, "å bestemme seg", can be translated as "to make up one's mind". So if the sentence was "Han bestemte seg for hva han skulle spise", it implies that he needed a bit of time to make up his mind, while "Han bestemte hva han skulle spise" means that he was more decisive.
The sentence above is asking somebody to make a desicion for you, so you want them to be decisive. :)