President Obama, in his speech at the DNC, used the phrase "That is not the America I know." Donald Trump Jr. claims this was plagiarism, as he had used the same line in a speech he delivered last week.
The context is Melania Trump's own obvious and lengthy plagiarism of several sentences of a Michelle Obama speech. Thing is, "not the America I know" is such a common turn of phrase that it retreated long ago to the world of political cliche. Among those who used it before Trump Jr.? Hillary Clinton. George Bush Jr. And, of course, Obama himself, at an earlier date.
Trump Jr. quickly followed up to claims he was just trolling.
Suuuuure you were.