The idiom "dumbfounded" comes from the pre-Qin "Zhuangzi Dasheng", which is used as an adjective to look ** because of fear or surprise, and also extended to mean that someone seems a little stupid or **.
There is a phrase in English that means very stupid, such as.
Example sentence 1】I used to think she was dumb as a post when we were kids, but she grew up to be a particle physicist(When we were kids, I used to think she was stupid, but she grew up to be a particle physicist.) )
Dumb as a Post can be replaced with Coal Bucket, Stump, FencePost, Brick, Box of Rocks, and more stupid can be replaced with Ox, Sack of Hammers, Rock, DoorNail, Doorknob.
There is still a distance between the meaning of dumb as a post and "dumbfounded". In fact, in the original work of Zhuangzi, "wooden chicken" refers to being able to remain calm in times of danger, which is a compliment. Modern usage also emphasizes being frightened, not really stupid or demented.
be frightened out of (one's) WITS has the meaning of "scared soul not possessed", such as:
Example sentence 2] I was frightened out of my wits when you snuck up on me like that!(When you sneak near me like that, I'm scared!) ）
Another phrase is be frightened to death, as:
Example sentence 3] i'm frightened to death that the tests are going to come back positive.(Tested positive and I was scared to death.) )
Because of the different cultures, it is difficult to find a particularly precise and chicken phrase for "dumbfounded".
English can be as good as wood bird, wooden bird. The former is a bird of the forest, and the latter is a bird made of wood. So wooden chicken should be wooden chicken.
Wooden does have the meaning of stiff and silly, such as wooden actor and wooden performance, but wooden chicken has not yet been used.