Then she'll get a (Gelek-sized) tankard of water off a shelf outside of his line of sight (which definitely wasn't there earlier) and hand it to him.

"I think it would be a good idea for you to receive some medical attention. I employ a physician who can perform a simple spell to detect most things that plausibly could be seriously wrong with you. Is that alright?"

He will drink the water in a single long draught, after giving it a sniff to confirm it's purity. 

"I don't suppose I can prevent you." 

He would quite like some medical attention, honestly, but hallucinations are terrible doctors and goblins are worse. 

"I believe it's in your best interests, but not so likely to be urgent that I would proceed over your objections."

Would he like to swap his tankard for another, full, tankard she just grabbed from somewhere else out of his line of sight?

He supposes he would like some more to drink. 

"I would rather not." (Experience hallucinations of interactions with some shaman.) 

"Very well. Is there anything you would like to eat? We have some stew and rice, though perhaps not enough for your appetite, and I can get you anything uncooked easily enough."

"I would be quite happy to have any food you have worth eating, if you have it going spare."

Hallucinations of eating are probably better than not eating at all. 

Sure, here's a table with (human-sized) a pot of stew, a pot of rice, several loaves of bread, several hams, (Gelek-sized) a bowl of salad, a bowl of apples, a plate, a bowl, utensils, and a napkin.

Finger-food and vegetables. ... Better than an empty belly, but it's not mammoth. He'll take it, and eat with gusto and lack of either utensils or decorum. 

She will allow him to eat in peace, and get him more food if he looks like he's still hungry. It's all uncooked stuff out of the pantry, unfortunately.

Uncooked food is quite fine with him. He will eat extensively, putting down enough food to feed a thousand humans and then some more for afters. It's been some time since he's had a chance to eat to satiation. 

Once he is full, he will remember that he has a host. 

"Thank you. I apologise for my lack of table manners." 

"It matters little."

"Why do you believe you're hallucinating?"

"Because you are impossible, and I have 'coworkers' who think hallucinogenics are an amusing jape." 

"And are you experiencing any other characteristic effects of hallucinogens?"

"Your speech is not operating in the manner speech is supposed to." 

"Yes, that's a magical translation effect. My work. I don't know your language, although I'm capable of repeating things you've said. 'You are impossible.'"

"That sounds like something a hallucination would say." 

"Hmm." (He thinks for a moment and then switches languages.) 

The wicked usually attribute,

whatever faults they have to others,

Crows diligently wipe on something clean,

Their beaks they've dirtied by eating filth. 

What does that mean?" 

She repeats it in the language she's speaking, though the meter is different.

"That's a literal translation, if I wanted to preserve the meter I'd say this."

And she recites a poem in the language she's speaking which sounds, to him, like it means mostly the same thing, with some differences in sentence structure and word choice, and identical meter.

"I am reasonably certain you're not a goblin, then. I am quite certain that no living greenskin speaks a word in Sky Titan that isn't a loaned curse." 

"And are the hallucinogens you're familiar with capable of causing you to hallucinate this?"

He thinks. It's easier than it might have been, but he just had a heavy meal and sort of wants a nap.

"I think if I was drugged and when I woke up I believed myself to have been provided food and extemporaneous poetry in a made-up language by a hallucination of a beautiful woman, this would not be outside my expectations, for an experience goblin hallucinogenics could cause." 

"But this feels wrong, somehow, as a frame of reference." 

"Is there any experience you're confident goblin hallucinogenics couldn't cause?"

"This whole situation is very linear and calm, for a hallucination caused by goblin hallucinogenics." 

"Well, yes. That's because it's not," she says, serenely.

"So you say." The suspicion is starting to drain from his voice, though. 

"I don't really know what I could say to convince you it isn't, though I expect you'll persuade yourself of it eventually."