Well, I started by Googling for some Rhyming slang examples and let me tell you, there are tons of them "out there"... I liked this one and hope that my description of "suit" as "clothing" or "dress" will be on theme.
Whistle was another one hard to get. Either the angle was wrong, or there was something wrong with the form. Well, I ended up forming my own whistle using the source image.