I think traditionally the triangle instrument is supposed to have one corner unconnected..
GreenDrag said:
Yeah that's true... but the faces made here compensate for that mistake I guess...
If you look closely, you'll see that the shadows imply that it's a Penrose triangle. Either there are a lot of those in Gensokyo (being actively disbelieved in by humans), or Yukari is fooling around again...
*explosive blush*Ding-a-ling!
The sound made by the triangle is "chinchin", which is also slang for penis.