Lo Wang from Shadow Warrior had also almost as good quotes as Duke Nukem. Many are hilariously funny
Whoops, Lo Wang drop soap
I would also recommend (hard as bone and funny as hell) quotes from
Gothic 1, and also
Baldur's Gate II ambient sound and
NPC speech. However since the first is a game mostly known only in Germany, and the second has (in my opinion) so much better sounding, characteristic speech in German than in English, I guess not many of you would be able to appreciate it. Unfortunately, there're also no quotes from Baldur's Gate II in German on Youtube, it seems. Still, it's quite good in English, too.