While hunting aRawhead, huntersSam and Dean Winchester arm themselves with tasers due to the Rawhead's weakness being electricity. During the fight with the Rawhead, Dean is able to kill it with his taser, but as he is lying in a puddle of water that the Rawhead is also standing in, Dean is electrocuted as well. The conducted taser blast caused fatal damage to Dean's heart that nearly kills him.
AfterRandy Baxter finds the Winchesters in his office and begins calling 911, Garth uses a taser to render him unconscious.
To prevent Sam and Dean from finding out the true identity of Thinman, Deputy Tom Norwood lures them to the local mill and knocks them both out with a taser.
After Dean fights back when Sheriff Ben Anderson tries to keep him from going after Sam, Anderson uses a taser to render Dean unconscious.