How to briefly crash somebody's internet connection?

I was recently playing an online game against a rival opponent, A few seconds into the game I lost connection which counted as a forfeit and cost me the match. I assumed that my provider had a little problem, so I went back into the lobby and by co-incidence was matched up with the same guy. Once again, a few seconds into the game my internet crashed, I was kicked from the game, and he claimed a win. When I complained he told me that he was doing it by forcing my internet to momentarily crash. I asked him how he went about doing this, but he wouldn't elaborate much. He did claim that it had something to do with bot-netting and that he obtained my IP address from a picture of his I viewed, which was necessary. Is this guy for real or messing with me? If this is possible, can anybody do it? How would I go about it if so? Thanks so much for all the help.
Edit: This is performed on PC, not XBOX live and its on a massive online multiplayer game.