Question: Several months ago, I was in a session playing as a bard wanting to distract some bugbears while he snuck past. Understanding the goblinoid tongue, I heard one of them state he was starving. I used the phantasmal force spell on one of the bug bears, lets call him BugA. The desired effect was he would see one of the other bugbears as a pile of delicious food(BugB).

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> The phantasm includes sound, temperature, and other stimuli, also evident only to the creature.
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BugA began to eat BugB, who of course, was not pleased about this and attempted to protect himself, mainly by attempting to hold BugA back and producing a **lot of noise**.
Does the phantasmal force spell make BugA unable to hear BugB's shouting and requests for BugA to stop? (considering BugB is effectively obscured by the illusion) 

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> For example. a target attempting to walk across a phantasmal bridge that spans a chasm falls once it steps onto the bridge. If the target survives the fall, it still believes that the bridge exists and comes up with some other explanation for its fall-it was pushed, it slipped, or a strong wind might have knocked it off.
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Unlike the bridge example of the Player Handbook, the illusion covers a character that would be shouting and defending against the actions of the target of the spell. Would BugA continue to make excuses or ignore the noise produced by BugB? 

To put it another way, if a source of noise is inside of an illusion of a box, produced by the spell phantasmal force, can it be heard by the individual who can see the illusion?

Answer: 
**Yes, the affected target can hear the other bug bear, but it might not matter because illogical outcomes are internally rationalized by the affected creature.**

Source: PHB pg. 264, Phantasmal Force

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> The target rationalizes any illogical outcomes from interacting with the
>  phantasm. 
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So if the other bug bear was screaming at him because he was being eaten, the one who was affected by the spell might make an Investigate check to discern the illusion. But if he failed, he may rationalize screaming food as:

1. Another bug bear trying to wrest away his food;
2. A commotion in a different room nearby;
3. His own internal thoughts pestering him for being so gluttonous;
4. etc.

However, a key bit here that's been missed is that the affected bug bear is not compelled to eat by the spell just because it is hungry. So it wouldn't necessarily attack a giant plate of food that's arguing with it. It may just end up arguing with the food. At this point, it's entirely in the DM's hands to roleplay this out. 

It's certainly a creative use of the spell, but understand the illusion would simply make the other bugbear look like food. It wouldn't actually make the affected bug bear try to eat him, especially if the food ran away or started fighting back.
There are problems with this use.
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First, Phantasmal Force only *creates* illusory objects, not *replaces* real objects. You could have a pile of delicious food seemingly surround BugB, but if the BugB steps out of Phantasm's area of effect, he stops being affected at all by the obscuring effect of the illusion - BugA would likely rationalise it by having BugB emerge from beneath the hams and cabbages. 

Second, it is for your GM to adjudicate whether you could control the phantasm so finely as to make it follow BugB. The wording is silent on movable phantasms, such as creatures, going out of it's initial zone and refers to phantasm's position. It is arguable whether the phantasm is essentially immobile or can be moved, but make note that spells with movable areas of effect usually mention that the caster can use their bonus action to reposition the effect and make it deal damage. Phantasm is unique in a way that it deals automatic psychic damage as long as target is within or 5 feet away from the phantasm with no action required. 

Judging from the fact that it's a 2nd level spell I would rule it's confined to the initial area. A mobile illusion spell, 3rd level Major Image is completely harmless, while the first damaging illusion that targets a creature instead is Phantasmal Killer at level 4. I think it would be pretty overpowered if you could move your illusion outside of the initial casting area.