Arien and Lilly Pad are very close friends (though undisclosed sources hint at a bigger relationship between them) ever since they were little. They got separated when Arien decided to travel the world but have kept in touch. Thanks to their travels, Arien's language is more refined than the rest of his kind... but they still lack some knowledge on common slang, for instance his complete lack of understanding of the "thicc" term, nor how sensual he's considered to be by everyone else around him. How and when Lilly heard this term? No idea.
There you go, enjoy Arien at the full might of his thiccness! ^^