Is this cockney rhyming slang?

Frankly, I have no idea! I would assume the speaker means that "it", whatever that may be, may go lumpy and undesirable?

What I do like is the fact that you can write English properly, thumbs up! If I could thumbs up questions, of course!

In Cockney Rhyming Slang custrad usually refers to custard and jelly = telly but this does not seem appropriate.

An alternative is custard tart = heart or sweetheart but again this does not seem right

Probable is custard cream (a type of biscuit) = dream i.e. it is not going to work out.

I have not seen the film but was the character Australian? If so, it could be Australian Slang for Pimples or Spots (from the colour of the pus)

These are cockney rhyming slang

Apples and pears = stairs

Whistle and flute = suit

dog and bone = phone

I don't think it'll all go to custard means it will do not good

Like 'all go sour' but these are not cockney slang

ahhhh i love cockney slang its so fit!!! give me a cockney geeza any day!

sorry that doesnt really answer ur question...just wanted to show appreciation for cockney lads!