What does “Stick it up one’s jumper” mean? Why is it funny?

I saw the phrase “Stick something up one’s jumper” in Jeffery Archer’s short story titled “Member’s Only,” in which Robin Chapman, the hero was kept waiting for 5 years and has to wait for another unknown number of years for being admitted to be a member of the distinguished Royal Jersey Golf Club in the birthplace of Harry Vardon.

The phrase appears in the following conversation between Robin and his wife before Robin attends his second interview by the Club committee after being listed on the waiting list 15 years ago:

‘Good luck, and don’t even hint at how angry you are. It’s not their fault that Germans destroyed all the club record.’

‘I shall tell them they can stick my application form up their jumpers,’ said Robin.

They both burst out laughing at the latest expression they’d picked up from the mainland.

‘Do they have any idea how old I’ll be in 15 years,’ he added.

From the nuance of the context, I guess “stick something up one’s jumper” is similar to “carry it with oneself always.” But why is this phrase so funny that they burst into laughter when uttered? Does “Picked from the mainland” mean the phrase hasn’t yet established as the currency for a received English phrase?

Yahoo answer defines “stick it up one’s jumper” as

It was a catchphrase of the comedian Jimmy Edwards. In the 1950s it was considered quite rude because it included the words 'stick it up'. It has died out since then.

I don't know if it applies to the present case or not.

Solution 1:

This phrase is a modification of the crude, informal present-day phrase, "You can stick it up your ass."

This phrase indicates two things: The person speaking does not care about it, and the person speaking does not like the person who is being targeted in the phrase. "Carry it with oneself always" is a good guess, but this phrase doesn't have that meaning at all.

The use of "They can stick my application form up their jumpers" is used to say that the not only does the speaker not like the people who have his application, and he also doesn't care about the application. "They can stick my application form up their asses" would have been about the same thing, except that in the phrasing the speaker used, he's probably making fun of them for wearing jumpers, too.

This phrase is very rude and not a very good "joking" insult -- it should only be used when you really don't like someone!

The humor comes from the fact that the speaker has used this phrase to declare his contempt for the people involved in a round-about way. I wouldn't say it deserves bursting into laughter, but there you go.

Solution 2:

Stick it up your jumper seems to be similar to stick it up your ass. As this site explains, both mean:

colloq: A contemptuous exclamation that is used when something is not wanted, not going one's way, etc.

The Shorter Dictionary of Catch Phrases adds that the full phrase is oompah, oompah, stick it up your jumper and its origins are:

an expression of contempt, defiance, rejection, or dismisal; perhaps originally a meaningless jingle chanted jocularly or defiantly. The phrase dates from the 1920s. The word oompah is imitative of a trumpet, trombone, or other brass instrument.

So the speaker was thumbing his nose at the people who put him on the waiting list for 15 years. Do not use this phrase in common conversation, unless you are deliberately abusing someone.