Appears to be a bot programmed to look for open proxies.
Dreamquick
8:27 pm on Dec 9, 2002 (gmt 0)
Normally they would just use a GET if they were after open proxies, I'd expect to see a CONNECT used to check if the service allows connections on user-defined ports to be bounced through it.
Since CONNECT is normally disabled or unsupported if they got a good result then they could come back and do a more thorough test.