Yeah. Ruby's URI module is pretty loose on the definition of a URI string (RFC2396), but it is still possible to use a weird looking URI that forces it to raise InvalidURIError when parsing.  Here's an example:

	1.9.3p392 :014 > URI("##")
	URI::InvalidURIError: bad URI(is not URI?): ##
		from 	/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/uri/common.rb:176:in `split'
		from 	/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/uri/common.rb:211:in `parse'
		from 	/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/uri/common.rb:747:in `parse'
		from 	/.rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/uri/common.rb:994:in `URI'
		from (irb):14
		from 	/.rvm/rubies/ruby-1.9.3-p392/bin/irb:16:in `<main>'