I've often been seeing phrases like the following lately:
s/he has been stood
s/he has been sat
used instead of the present perfect continous i.e.:
s/he has been standing
s/he has been sitting
It's usually only used with sit, stand or similar verbs of position. Now, I'm not a native speaker and I've never come across this until a few years back, but it doesn't stike me as a rare occurence by now.
My question is: What kind of idiom is this? / Where is it used?
PS: If this construct is ungrammatical and you want to point this out, please do so in a civilized way. I mean, I guess it is, but I'm not into the kind of disdain that regularly comes up in that kind of discussion.
Edit: I was ask to provide context, which I see is necessary as some commenters pointed out correctly that the first construction is of course perfectly grammatical as a passive construction. I'd like to stress that this is not what it's used for in this case. It is really used equivalently to present perfect continuous. It has also been mentioned by one commenter that there exists a confusion between sit/set/be seated and lie/lay ('lie' could be another candidate for the use I described, but I'm not sure), but I'm uncertain if this has anything to do with this, especially as there's no such confusion with 'stand'.
Two exemples would be:
Bob, who has been stood outside the door smoking, comes back inside.
The baby grand piano has been sat in Fiona's front room for a grand total of three months now.