A coke and an egg is perfectly healthy. A coke is ~150 allergen free calories, with a useful dose of sodium and some caffeine. An egg is a good bolus of protein, minerals, and vitamins. The only way I'd consider that combo unhealthy is if the person in question happens to have an egg albumin allergy. On the other hand, soylent has glaring problems with its ingredient list. I would never eat it and consider it garbage.