Ear Hacks
Ear Hacks (or Ear Hax), is a Counter-Strike term coined by Octwo, used to sarcastically refer to a person's ability to hear another person within a game well enough to give others the impression that they're "wall hacking."
Bob hears Joe walking on the other side of a wall. He fires his weapon at Joe as he hears him near the edge of the wall, killing Joe through the wall without first seeing him. Joe calls him a wall hacker, so Bob rolls his eyes and sarcastically says that he was using Ear Hacks.