An individual who seeks food in any situation where no exchange of capital is needed, e.g., dumpster diving or crashing a wedding buffet
As an opportunivore, Lance preferred sponging off of friends rather than braving the cold, wet dumpsters.
Someone who selfishly exploits
or takes full advantage of any situation involving free food or items.
The opportunistic omnivores
in the office will eat anything we leave unattended in the kitchen, and now those opportunivores have eaten all the Christmas cookies.
jerk took all the free condoms from the clinic, they're such an opportunivore.
Someone following the "high-everything diet", i.e. high-fat, high-carb, and high-protein, without any restriction on calories or macro-nutrient ratios. Could be a competitive eater, big body-builder, or just a normal person who will eat anything.
An opportunivore will eat whatever is available.