The chess writer Tim Krabbé, whose wonderful Open Chess Diary Bill mentioned the other day, once wrote about a game in a simultaneous exhibition he had given that began 1.e4 Nf6 2.e5 Nd5 3.d4 e6?! 4.c4 Bb4+? 5.Ke2! Having moved only pawns and his king, Krabbé had a won game, since Black loses a piece after either 5...Ne7 6.a3 Ba5 7.b4 or 5...Nb6 6.c5 Nd5 7.a3 Ba5 8.b4. Unfortunately, at this point someone noticed that the king and queen had been set up wrong in the initial position, so Krabbé agreed to restart the game from scratch.
As the game below shows, one can trap Black's bishop exactly the same way on the kingside. After my 5.Qd2! Black was losing a piece just as in Krabbé's abortive game. Note also the variation 5...Ng6 6.f5 Ne5 7.h3 Bh5 8.g4 Nxg4?? (8...Bxg4 9.hxg4 Nxg4?? is similar) 9.Bb5+! c6 10.dxc6 and the dual threats of 11.cxb7+ and 11.c7+ are crushing.
The rest of my game was very uninteresting, alas, as my opponent hung all his pieces.