It is when two people do not agree with something, for example, when Trump makes racist comments, two people disagree with him so they agree to disagree.

Saying invented by joe

When someone have a really stupid opinion but you don't have the time or energy to debate them so you just want to cut short the conversation and get some of the sense of moral superiority you would've get by proving them wrong.

When you firmly yet gently disagree with what Team Plasma said years ago.

Refers to a "buddy assistance" deal where Person A completes a yucky/difficult/boring job for Person B that he doesn't feel up to suffering through, while Person B tackles a similarly-sucky task that Person A would ordinarily have to perform himself, but also loathes the thought of doing.

When two or more people think their own opinion is correct when only one person is right