Keywords are inclusive, so the more keywords you put in, the less lines you'll find.
You can specifically ask for a keyword to not exist by prefixing it with !.
For example, searching for "mouse !cheese milk" would find lines that contain both mouse and milk but not cheese.

[050827 11:11] 6edf8, Kay: For those truely interested in a place more like the 'old days' might want to check out R'leyh rebuilt and reopened *yes, is advertising!*