I always though that "Bigtibs" was some sort of ceremonial greeting that I didn't understand. Turns out he says "Victims of the Almighty Sarlac..." Now that makes more sense.
I also thought he said, "But should some of you wish to beg for mercy the Great Jabba will NOT listen to you pleas." I though, wow what a heartless basterd. Turns out he says "...the Great Jabba will NOW listen to your pleas." Now I think...wow what a heartless basterd because he's gonna kill them anyway.
I also thought that during the line that Han says "3PO, you tell that slimey [something] he'll get no such pleasure from us! Right Chewie?" And Chewie agrees with him and growels "No." - as in "you are correct Han, he won't get that pleasure from us."
But I always thought his growel meant "No, are you kidding? I'm totally going to beg for my life here." I think my version is funny.