It's a copy and pasted block of text usually posted on a message board to troll newer users and as an inside joke between older users. Copypasta can usually be found posted in a discussion about any subject, and will usually be intended to draw out newer users into responding negatively to it, much to the amusement of more veteran users.

Copypasta might have started out as a real post somewhere, but people might have found the story so stupid or amusing that they post the exact thing years later to mess with people. It's much like a group of friends getting together to mock what another person said in the past and laughing about it.
User 1 posting copypasta:
"Hey Faggots,
My name is John, and I hate every single one of you. All of you are fat, retarded, no-lifes who spend every second of their day looking at stupid ass pictures"

User 2:
Hey, I'll kick your ass for talking like that

User 3:
"lol, look at this guy replying to copypasta"
by Ihaveavianflu76 November 8, 2016
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A derogatory term for forum posts which contain a direct or nearly direct copy-and-paste of memes, posts from older forum discussions, or other material, often accompanied by an attempt to pass off the contents as new and original.

Commonly seen on 4chan.org's Random ("/b/") forum.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.

DAT'S SUM DELICIOUS COPYPASTA
by BURT ROGES December 1, 2006
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A derogatory term for forum posts which contain a direct or nearly direct copy-and-paste of memes, posts from older forum discussions, or other material, often accompanied by an attempt to pass off the contents as new and original.

Commonly seen on 4chan.org's Random ("/b/") forum.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.

DAT'S SUM DELICIOUS COPYPASTA
by TRUB SEGOR April 29, 2010
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A derogatory term for forum posts which contain a direct or nearly direct copy-and-paste of memes, posts from older forum discussions, or other material, often accompanied by an attempt to pass off the contents as new and original. Commonly seen on 4chan.org's Random ("/b/") forum.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.

DAT'S SUM DELICIOUS COPYPASTA
by taylen24 June 11, 2010
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1. An amount of lengthy text that has been repeatedly copied from somewhere and pasted as a reply to an irrelevant subject.

2.An alternative version of the slang term "copypasted".
1. "Dude, how was Monday night?"

"Don't say another word. Up until now, I've been polite. If you say anything else - one whisper of a word - I will destroy myself. And when my tainted spirit finds its destination, I will topple the master of that dark place. From my black throne, I will lash together a machine of bone and blood, and fueled by my hatred for you this fear engine will bore a hole between this world and that one."

2. "Your bio is fake? It's all copypasta?"
by Elexus April 21, 2006
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A derogatory term for forum posts which contain a direct or nearly direct copy-and-paste of memes, posts from older forum discussions, or other material, often accompanied by an attempt to pass off the contents as new and original.

Commonly seen on 4chan.org's Random ("/b/") forum.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.

DAT'S SUM DELICIOUS COPYPASTA
by Lycheems December 11, 2020
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A derogatory term for forum posts which contain a direct or nearly direct copy-and-paste of memes, posts from older forum discussions, or other material, often accompanied by an attempt to pass off the contents as new and original.

Commonly seen on 4chan.org's Random ("/b/") forum.
> I went to Taco Bell and tried
> to spend a $2 bill, and the
> cashier had no idea what it
> was and called the cops.

DAT'S SUM DELICIOUS COPYPASTA
by totalfuckingidiot November 3, 2020
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