Not that you need to do

[Maybo]

Liam stands up, and I notice that while the two boys are about the same height, Tyler is broader like the football player he is. Liam has more of a runner's physique. I'm scared that in a fight, Tyler would have the edge.

But Liam doesn't look the slightest bit intimidated.

He looks Tyler right in the eyes. "I didn't trip you. You're just clumsy."

Tyler snorts. "What? Are you trying to show off in front of your girl? Not that you need to do much to impress her."

Source: The Perfect Son by Freida McFadden

Does “Not that you need to do much to impress her” mean “It’s not necessary that you need to do much to impress her”?

 

[jutfrank]

The missing words are:

It's not the case that you need to do much to impress her.

The meaning is that it's very easy to impress her. This is meant as an insult to both the girl and Liam.

 

[Maybo]

It is not in any way Luke's job to get me coffee, but I know from experience that he will insist on getting it despite my protests. So instead, I nod. "Thank you."
He winks at me. "One cream, no sugar." He's got it right. Not that I'm surprised.

Source: Never Lie by Freida McFadden

Are these the missing words for “Not that I’m surprised”?:

It’s not the case that I’m surprised.

Is the meaning I’m not really surprised that he’s got it right?

 

[emsr2d2]

Are these the missing words for “Not that I’m surprised”?:

It’s not the case that I’m surprised.

They're not missing. They're implied/understood.

Is the meaning "I’m not really surprised that he’s got it right"?

Yes.

 

[jutfrank]

They're not missing. They're implied/understood.

They're missing logically/syntactically in the sense that the sentence is not logically or syntactically complete without them. In strict terms, it's not quite right to say they're 'implied', since implication does not generally apply to words but rather to thoughts, beliefs, opinions, intentions, etc.

 

[Maybo]

"Uh-huh." I run the faucet and scoop up a little water with my hand to rinse out my mouth. I hate vomiting.

Not that anyone likes vomiting, but I find it particularly distasteful. "I'm fine."

Source: Never Lie by Freida McFadden

The speaker is pregnant so she vomits.

Have I understood correctly for “Not that anyone…”?:

“It’s not the case that anyone likes vomiting”

Also, I looked up “Not that” in a dictionary, I’d like to know that should I understand the two definitions in the dictionary as the above sample sentence? Or are they completely different things?

 

[jutfrank]

This writer really likes 'not that' sentences, doesn't she?

“It’s not the case that anyone likes vomiting”

Right.

It's like saying 'I don't mean to suggest that anyone likes vomiting.' The idea of the 'not that' sentence is to say that the verb 'hate' is not meant to contrast with 'like'. What she means is that although everybody dislikes like vomiting, she strongly dislikes it.

Also, I looked up “Not that” in a dictionary, I’d like to know that should I understand the two definitions in the dictionary as the above sample sentence? Or are they completely different things?

Forget about what the dictionary says and focus on what we're telling you here on the forum about each particular sentence in context that you ask about.

 

[Maybo]

Tonight, we're eating Kraft macaroni and cheese. And anybody who says a d*** word about it will have their plate yanked away from them and hurled into the garbage.
Not that anyone will care. Both Hannah and Liam have barely eaten anything.

Source: The Perfect Son by Freida McFadden

Does "Not that anyone will care." mean "I don't mean to suggest that anyone will care."? Although nobody will care about what she does, she will hurled the food into the garbage if anyone has opinions about it.

 

[emsr2d2]

It means no one will care if she does throw the food away. The fact that they've hardly eaten anything suggests that they're not enjoying the food anyway, so threatening to throw it away isn't really much of a threat.