It goes something like this after giving a basic description of an item: Wouldagive 90, 90, 90 now 100, 100, couldabid 110, 110, I'm lookin for 120, 120, but it goes relatively quickly. At the beginning and at different times within the chant, the increments can go down (if there aren't any bids) or up at a different increment level if the item is hot and bids coming in swiftly. There are many "filler" words that can be placed in between the numbers, as well as various tongue twisters and other chatter.
Bid Calls or The Chant is the method the auctioneer uses to let the audience know where the pricing is at for a given item as well as to entertain and make the process of auctioning as interesting as possible.
The real purpose of the auction and the chant itself is for the auctioneer to get the best possible price for their client.
Some auctioneers spend a lot of time developing different chants and there are actually chant competitions. Some auctioneers have a chant that is so fast that the current amount level is virtually unintelligible but experienced auction goers are able to distinguish where the auction pricing is at and able to understand the cues given by the auctioneer.