Friend: I think it's the cable. Do you have another cable?
Me: Let me check. (returns with huge bag of extra cables and cords and various computer parts.)
Friend: Whoah. That's sexy.
Me: Hey, look, extra DSL filters.
Friend: Really sexy.
It wasn't the cable (or the filter, which I changed), so then he thought it might be the modem.
Me: (rummaging in bag) It turns out that I have another modem in here.
Friend: Hey, cool. There's a lot of stuff in there.
It wasn't the modem, so he determined that it was the computer itself that was the problem.
Friend: It's probably the ethernet card.
Me: (rummaging in bag) Here, I have one of those too.
It was really very entertaining. ^_^