I heard people say this phrase once or twice, in derogatory tone. It sounds like 狗吃连帮 or 狗吃粮帮. Internet search gives no result, but it didn't sound like some local dialect to me.
I heard people say things like 他们这些人就是狗吃连帮 or 我们得提防着他们点狗吃连帮．Something like these．
@Semaphore,@NS.X.,I heard both people from Tianjin and Shandong say it. Maybe it's a saying that goes in Huabei area, like sayings like 不招人待见 go only in some parts of northern China (but which is now more generally known). I asked those people what they meant by this 狗吃连帮. One says it means 一帮人勾结起来做坏事, but he's not sure how to write "lian bang". Another says it means 一撮人私底下谋划陷害别人, written as 狗吃连邦. But she's not sure how to interpret 连邦 literally, preferring to view it as a slang that's oral in nature.