K: "K" is for curt and the texting equivalent of the middle finger. They have nothing left to say.

Yes.: Meaning, they are not happy about what they just agreed to.

Sure.: The period at the end sounds annoyed or dismissive, like the person you're texting has an attitude.

Yep: Implies an upbeat worry-free attitude, a la "yeah, totally, no problem!"

Yup: This is the pissed-off cousin of "yep" and indicates you've agreed to do something you don't want to do.

That's different: They're not a fan, but they don't want to disappoint or offend you.

That's fine: Obviously, it's not.

Umm yeah: Sarcastic response to a stupid question.

Thumbs up emoji: Intended to avoid conversation.

Ubetcha!: Perfectly acceptable at all times.