With this exploit, a lifetime donator can go medic with the amputator taunt and slow down their taunt speed using taunt poser and set it to 0x speed. If you're around the amputator healing range and switch to the other team you will regen health until you're back to full hp. This bug only works if the medic on the other team is alive. With doing that, the taunt will go on until the medic dies, changes classes, or leaves the game.
Bug demo: demo15.dem