What does ‘Jam down one’s throat” mean?

I came across the phrase “I’ll jam down their throats” in the following sentence of the Reuters’ article (June 30 issue) dealing with the Davis Cup, titled “Pat Rafter Wary of 'Awkward Chinese.'”

Our biggest problem is if we are complacent and we take them easy," he said. "That will be the one thing that I will jam down their throats—they will be very tough.

In search for the meaning of the phrase, I found a similar phrase, “jam one’s belief down someone’s throat” in the following example. .

I mean, vegetarians and vegans don't try to moralize or jam their beliefs down everyone else’s' throats, right?—www.foodaq.com/html/General/44813.html.

What does “jam down something one’s throat” mean? Does it mean to force someone to swallow (accept) something or surrender to someone? Is this a popular phrase?

Solution 1:

Jamming into one's throat means to make absolutely sure the person hears you and cooperates with whatever you're jamming into his throat.

So the captain, Pat Rafter, is saying that he'll make absolutely sure his team gets the message that they can't afford to be complacent when playing against the Chinese. They've got to be tough, or they won't win.

And the point made in the other example is that most vegan/vegetarians don't force their views on everyone else, or even look down on others, as some people seem to think.

If you're planning to use this expression, consider a more common form: "shove down one's throat". This NGram illustrates that "shove down his throat", though rare, exists; whereas "jam into his throat" does not even appear. (The same goes for "their throats", and, I assume, all other forms.)

Solution 2:

To "jam" is force into.

To jam something down a person's throat, is to force a notion, or idea into somebody. It is to force someone to agree with your idea.

So, in your excerpt, Pat Rafter is saying that he needs to force "them" to understand that their biggest problem is to become complacent and take the opponents easy.

This is backed up by your second excerpt, in which the author is saying that vegetarians and vegans don't go around trying to force everyone to become a vegetarian or vegan.