I'm pretty sure it was the 2008 ISMRM meeting (small chance it may have been 2003). I don't think it was actually submitted, because I couldn't find it in the proceedings even back then. I think whoever it was smuggled the poster into the hall and hung it among the others as a prank. I'm pretty sure the dead salmon fMRI poster was also there at the time but I can't remember if that was in the proceedings. The dead salmon fMRI did end up being published though and making quite a stir.