Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. Nc3/3...dxc4/4.e3/4...b5/5.Nxb5/5...cxb5/6.Qf3/6...Qc7/7.Qxa8
White thinks he has won material, has he? White will be in for a rude awakening, however. His queen is about to be trapped! Of course, the only move that even tries to trap the queen is Bb7 (If Nc6, there is no threat, the c8-bishop is now pinned, and white can play a4 with a winning game). However, it sacrifices another pawn on a7, so many people would fear this line and go for 7...Nc6, which loses.