The rhyme isn't usually so obvious as bread/dead. Usually the rhyming part of the phrase is hidden. So much so that people use it without even knowing it's (rhyming) slang.
Butchers is a case in question, 'Let's have a butchers,' means 'Let me look at that.' The rhyming phrase is Butcher's hook - look, but the hook is dropped. It's meant to confuse, like a thief's cant.