I found this passage from a news article and they make mention of a dry snitch:

"These guys have double standards: When it's OK for them, they rat," said Alite. "John Gotti Sr. sat in a room and talked about crime after crime and blamed them on Sammy Gravano. That's a rat. That's a 'dry snitch,' and in our laws that means that man needs to be killed."[i][/i]