Made popular by Lee Evans, it is the chair/bench that if found generally next to changing rooms in clothes shops. Men are placed here to wait for their wives/girlfriends/lady friends, usually with a bewildered look on their face as they take in their surroundings.
"Ha look at him on the bewilderment chair! He don't know nothing!"
"Alright love, don't be long, i'll just be here on the bewilderment chair"