The best opening line I ever heard was from a London-based epidemiologist. I forget his name but he was debating "pharmo-genetic illness" with Ivan Lorenz, who headed an American think tank, and who had just published a book detailing the high incidence of illnesses caused by medical treatment.
The debate was so complex that I bought a printed copy so I could read it more closely and, even with that, Lorenz's formal opening statement was so convoluted that it was hard to follow.
Then the doctor stood up to speak and won the audience and the entire debate with his opening remark. He said, "I think that's a load of bullsh1t".
That's my kind of debater. >:-)