Ignore proxy

Please ignore this message if it is a FAQ.

I wanted to know if there is a way for a proxy to tell a client
any/all of the following things:

1. Ignore me and fetch this document yourself. (but if you call me
again I might change my mind.)

1a. Ignore me for some time.

2. I will not fetch this for you.  (the "Not Authorized"  response?)

2a. I will not cache this for you.

I see this as a way (analagous to "Come Back Later") for a very busy
proxy to tell clients that they are on their own.  Also, a caching
proxy might want to tell a user agent that it will not cache its
requests.  Of course, there are problems with proxies which are
gateways -- they should never refuse proxying, but still might refuse
caching.

Thank you in advance.