When talking about a particular food or meal, eat and have can function interchangeably most of the time. Of the two, have is the more versatile and generic word:
Let's start with your last example:
I'm eating pizza now. Let me call you back – I don't want my pizza getting cold.
I'm having pizza now. Let me call you back – I don't want my pizza getting cold.
I see no real difference in those two statements. I think I'd be more likely to use the first, but the second wouldn't jar my native ear.
Then your breakfast example:
I eat breakfast every day at 8 o'clock.
I have breakfast every day at 8 o'clock.
Once again, either one of those is okay, although the second sounds a little bit more formal for some reason. In its seventh definition for have, Macmillan mentions:
have (verb) [TRANSITIVE] [NEVER PASSIVE] to eat or drink something. This word is often used in polite offers and requests
- Can I have another piece of that delicious cake?
- Let me buy you a drink. What’ll you have?
- Why don’t you stay and have lunch with
us?
I’ll have (=used for requesting food or drink in a restaurant): I’ll have the roast beef, please.
There are a few places where the two words aren't interchangeable. The end of that definition gives one example; if I was ordering at a restaurant, I wouldn't say, "I'll eat the roast beef, please." That might be true, if that's what I'm ordering – but it's simply not idiomatic to say it that way.
Another clue is that have is always transitive. So, it's perfectly fine to say:
I'm starving – let's eat!
but you wouldn't be able to say:
I'm starving – let's have!
Here's one more odd case:
I'm hungry; let's have at that hamburger place.
I'm hungry; let's eat at that hamburger place.
In this case, we can't use have to mean eat, because we're not using the word transitively. We can fix that by saying:
I'm hungry; let's have hamburgers at that place.
However, the first is not necessarily grammatically incorrect, because we could be using the phrasal verb have at. NOTE: This would be a very informal usage of have at, but I give it a mention because it shows how complex and flexible English can be, especially when dealing with informal expressions and eating food. When I was in college, one of my roommates might have said:
I'm hungry; I think I hear hamburgers calling my name!
Break down and break up are two different phrases with slightly different meanings. although both may be used to within the context of relationships, they're used in different ways. Perhaps it will help if I explain the origins of the phrases.
Break Down
This means to stop working, typically referring to a complex machine.
My car broke down on the M25 Motorway last night. It took me hours to get home
Sometimes we will use it to talk about a relationship stopping working too: mostly in this usage we are talking about the interaction, trust, love, and communication between the people breaking down. It usually implies that the relationship ending wasn't anyone's fault, and it was just the natural end of the relationship.
It does not always mean that the relationship ended instantly, and is more about the relationship problems, although it usually does indicate a break up which may or may not come later.
It describes the process of a relationship ending, not the actual event.
After I lost my job my first marriage broke down.
It will tend to be used about more serious, adult relationships - you are more likely to hear about a marriage breaking down, rather than the relationship between a teen couple.
Break up
This is the act of a relationship ending, and is the equivalent of a marriage divorce.
It comes from a more literal phrase 'to break up', meaning to physically separate into smaller pieces.
The spaceship entered the atmosphere and began to break up
This is used in a more literal sense than 'break down' in that it is talking about two people in one couple (larger 'object') separating into two smaller, separate objects (themselves).
Me and my boyfriend broke up when I saw him kissing Suzy after prom.
It may be used about both serious, mature, and less serious relationships, but is more often used regarding younger relationships.
Best Answer
The first example you give is fine and a fairly common idiom:
or
But, I'm afraid your own example makes no sense:
I suppose you could phrase it like this....
But I wouldn't use this myself. It isn't wrong, it is just unnecessarily wordy and subtracts from the impact of the hyperbole if anything.
Other similar expressions such as "not for all the tea in china" do not attempt to determine how much tea there may or may not be. It is just assumed there is a lot.