Numb

I read the following sentence in a novel, but could not figure out the meaning of "numb" used here.

" ... the family getting all gooey and sentimental about some numb thng the bratty kid did while he's having all his wonderful years or whatever."

Can anyone help me?

One meaning of numb is "devoid of emotion." But I don't think that is what is meant. I think "numb" must be a slang term meaning the same as "lame" as in square.