In MW2 I was playing Search and Destroy at the airport and I had planted the bomb right above the escelator. It was me and one enemy left. I saw him coming down the hallway past the bookstore, so I backed up...waited, and throw my Semtex grenade so it would land near the end of the hallway. But instead it stuck to the tip of his boot when he ran through the bomb site entrance. He jumped and got blown up!
I had Fraps running in the back, and since it was a round winning killcam, I got the chance to record the kill when the replay was shown. Which I did!