I don't know if you'd want to make it extremely clear that the employer is your first choice and you would like to negotiate your salary to a lower point. It seems like you'd want the exact opposite of that.
There's also a lot of powerful psychology about saying that you really want to work with them rather than playing hard to get. By saying, "you're my favorite!" (truth or not), you're establishing with them (in their minds) that you're an exceptional judge of character. :-)
But that is exactly what Google does actually do. Not on an individual basis mind, but as a general HR policy.