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.

[050621 01:59] 09b21, Peanut: anyone here anymore?

[050621 17:53] e84f0, Peanut: this place ever RP anymore?

[050621 21:55] ab4de, Peanut: matt is gay, he did the cyber nasty with me, and I have a penis

[050624 22:30] c7e9f, Peanut: Twas a War like no other that took New York and the Hamarantass...

[050624 22:30] c7e9f, Peanut: Mainly because noone bothered enough to actual fight said war...