Oh, how on the both worlds can I stay with an only one thing?! There are so much!
…okay, so ladies and gentlemen, sit on your lounge cushions and have some Kaja'Cola
It's an item found in Kezan, the goblin starting zone; its reagent is claimed to contribute to the goblins' independence.
While it's an obvious reference to fizzy drinks, it also makes a user express a silly thing, similarly to the Glyph of Confession (since Legion, that one is probably a toy). Of course, in this case, it's a consumable, themed a bit in line with the goblin kind of creativity (and/or decadence).
Sadly, you can't get it anymore past a certain quest (and surely after leaving the isle, of course). Moreover, the original item is unique (20), but at least it can be mailed or put on AH. A comment of Wowhead listing possible lines.
My favourite one is a BlizzCon reference. Who would have guessed that blues ARE such like greedy goblins, who at all?
Well. Kaja'Cola aswell as Glyph of Confession are an example of RNG that doesn't frustrate anyone!
They can have some RP usage as a conversation plot twist or as a fortune cookie, but we can also wonder what else would've been said by the affected people, hence go a bit deeper into the world by ourselves.
And an important lore question: has Rhonin had some Kaja'Cola after Algalon had been defeated?