Japanese Mispronunciations/Sun Deer
Joe intentionally pronounces various Japanese words wrong to annoy the weebs in his audience. Sometimes these phrases may also lead to the corruption of the English language.

This is a Joeism

When Joe says this, it's not a reference to any stream. It's just something he says sometimes.
"Tsundere", (ツンデレ, pronounced [t͡sɯndeɾe] [Soon-dare-ay]) is a Japanese word mainly used to describe a standoffish-but-warming character archetype in Japanese fiction, which Joe pronounces as "sun deer" instead.[1]
References
- ↑ “Joseph Anderson Channel Two” video: “Undertale First Blind Full Playthrough” at 00:56:43.