I managed to pull off the amusing trap below in an Internet game about a month ago. (My game began 1.d4 d6 2.Nf3 Nd7 3.e4.) Note that after 5.Bxf7+! Kxf7?? (5...Kf8! is best) 6.Ng5+, Black loses either his king (as in the game) or queen (after 6...Kf8 7.Ne6+ or 6...Ke8 7.Ne6, smothered mating the queen). On move 4, Black should have averted the bishop sac with 4...e6!, intending to play the Hippopotamus Defense with ...Bg7, ...Ne7, ...b6, etc.