A loose single curl or sickle tail pointing vigorously toward the neck and nearly parallel to the back is preferred.

松弛的单卷或镰刀状尾巴，尾尖指向颈部，几乎与背部平行的姿势是首选的。

youdao

"That tail tells you the direction the blood was travelling. So if your tail is pointing that way, which direction was your blood going?"

VOA: special.2010.05.05