Japanese people tend to shorten lengthy names, often by combining the first couple of characters of multiple words. Monster Hunter becomes Monhan, for instance. Dragon Quest becomes Draque. And so forth.
For Keiji Inafune's new PlayStation Vita multiplayer action title Soul Sacrifice, shortening the name via standard shortening "rules" would result in something that sounds a bit like "So Suck."
Inafune addressed this issue in a post at his blog today. "I'd like to you refer to this game as Soul Sack. Not So Suck... I think Soul Sack is better. Soul Sack. Soul Sack."
Of course, you also have the option of not being verbally lazy and calling it by the full Soul Sacrifice name.