In Call of Duty Modern Warfare 2, "aim-walking" is seen as one of the most devious forms of cheating. It usually involves, but is not limited to aiming down the iron sights or scope of your weapon while moving. In some circles "aim-walking" is seen as an aspect of the game the developers meant to include, but some of the most hardcore members of the fan-base believes its use is limited to "noobs" and "try-hards".
Player 1: I can't believe he killed me again! (Views killcam) Oh goddammit, he's an aim-walker.
(After the match is completed)
Player 1: You're such a fucking try-hard you faggot. I can't believe you were fucking aim-walking.
Player 2: What do you mean? I was just playing the game.
Player 1: Fuck you