Well, first, what you want to do is fire up your computer, plug in a second appliance (doesn't matter what kind) and as the advertisement starts to play, dip your finger in a glass of water, partially pull the second appliance out of the activated socket, and stick your wet finger in.
The resulting electric shock should incapacitate you for roughly thirty seconds, which gives the advertisement time to run its course. It's not skipping, but due to the voltage disrupting your natural flow of brain electricity, you won't even remember the ad occurring, so it'll be just like you did skip it!