CodeGuru: Un-Dynamics of Software Development, or, Don't Bite the Flip Bozo:
"# Don't say anything.
# Begin your statements with yeah, no a lot so that it sounds like you are being agreeable even when you disagree.
# Deliver the no at the end of the sentence. This is a technique that Jerry Hirschberg says the Japanese practice to great effect.
# Act like you are thinking about someone's bad idea before telling him or her it is crap. The crappier the idea, the longer you should wait before responding; hopefully, they will discover the inferior quality of the idea before you have to say anything.
# If you need a friend, get a dog."