 SPOILER. The "grey matter" that splatters on the wall when Jimi  (Shawn LeTang (qv)) blows the top of Tonias  (Melanie Ginnett (qv)) head off with his gun was a mixture of Karo  syrup based fake blood and a ground up slice of cheese pizza, that  was slung against the wall by FX artist (and Associate Producer)  Daniel Ingraham (qv).