In classic Cockney-speak, you don't say the word which rhymes with the object or person you are describing, but you do say the other word which is part of the phrase. For example, you would say to somebody who is unaccountably smartly-dressed, "Nice whistle, mate." (Whistle and flute = suit).

You might also say, "I didn't know you were up before the magistrates today", but that's beside the point.

Some of these associations require much experience, or a truly warped crossword-solver's brain to appreciate.

"Can I use your dog, mate?" (Dog and bone = phone)
"Sure, but if you just want to call a sherbet, there's one outside." (Sherbet dab = cab)