Multiple linedefs in vanilla Doom
From DoomWiki.org
Multiple linedefs in vanilla Doom is a demonstration WAD by Owen "Sarge Baldy" Lloyd released on 6 August 2003. The WAD uses a carefully positioned voodoo doll in a barrel crusher to simulate a switch that can perform more than one action, an effect otherwise impossible under vanilla Doom. However, the action has the side effect of dealing the player one point of damage.
