The Confederate flag is a divisive symbol in America and was used by the South during its civil war.
Its links to those who supported slavery 150 years ago means it is frequently associated with racism and adopted by white supremacists.
But it flies high above the South Carolina state house, the state where nine people were massacred in a racially motivated murder in a church last week, as regional law prevents it from being removed.
Speaking on Last Week Tonight, John Oliver said there was no place for the Confederate flag in America anymore except "on t-shirts, belt buckles and bumper stickers to help the rest of us identify the worst people in the world".
Is that a confederate flag on your belt, Leanne? Thanks for coming in, the nanny position has been filled.
Oliver pointed out many voters in South Carolina approved of its use - hence politicians such as Senator Lindsey Graham, a Republican, going through "comical contortions to avoid criticising it".
On Graham's comment that the flag "had been used in racist way", Oliver noted:
I believe the first time the confederate flag was used in a racist way was the exact second they finished sewing the very first one. It was around that time.