Here's something I remember from "The Challenge". Red, Boober and Gobo are trapped under a bushel basket.
Red: "I wonder what he (referring to Junior) wants with Fraggles."
Boober: "Gobo, we don't taste good, do we?"
Red: "I don't know, but still, I wonder what he wants with Fraggles."
Boober: "Probably baked potatoes and mushroom gravy."
Now that's just Boober being Boober. But...since Boober knows a lot about cooking, there's something else to consider. As a cook, he'd probably know what went went with what while making a meal. Aside from the rutabaga gumbo mishap, he was pretty successful at what he made. As knowledgeable as Boober is about germs, laundry, medicine and superstitions, you'd expect his research to be pretty thorough. He's one of few Fraggles to actually research something in a book.
As for the mentions of items in Fraggle songs, my theory is that they just hear these things, either from Matt's postcards or overhearing Doc. The Fraggles just have no idea what the words mean and put them into nonsense songs...just the way a lot of little kids would. They like the way a word sounds, then insert it randomly into a song. Or they might know that chicken chop suey is something to eat, but not know what goes into it. It's easy to imagine Doc ordering takeout from a Chinese restaurant while Gobo slips into the workshop. The rest of the Fraggle five could be behind the hole waiting for them:
"Here we are, Sprockie, two orders of chicken chow mein. It sure smells good!"
"Wuff, ruff!" (pointing to the other container).
"Ooh! Yes, here's the fortune cookies, too. You can open yours now while I get the mail...oh, here's another postcatrd for that 'Gobo Fraggle'." Doc tosses the postcard in the trash, Gobo fishes it out and runs back to the Fraggle Rock."
It never technically happened in the episodes, but it sure sounds like something that could happen.
Matt encounters "fast food" in one episode. There's the hot dog, but Matt doesn't eat it. He knows it's food, (he even says "fast food" aloud as he's carrying the tray over to the table) but he's too busy trying to figure out the physical speed of the food itself. With the exception of Aqua Teen Hunger Force, fast food doesn't move like that.
http://muppet.wikia.com/wiki/File:Matt_219.jpg
The mention of Gorgs fishing was in at least one episode: "The Gorg Who Would be King". Ma mentions that Pa can do all the things he wanted to do, like fishing and taking naps.
"But I do all those things now, plus I get to rule the Universe!" he complained.
Do we know if anything else exists in our world that would in the Gorg world? Fish do, as evidenced by Ma and Pa. Are "Outer Space" and the Gorg worlds connected? You think they probably wouldn't be, but unless you believe in some kind of Gorgish time/space vortex how would you answer this?
http://muppet.wikia.com/wiki/File:FraggleRock-511-Crown03.jpg