"I've Got Something Really Important To Tell You." is a pigflag joke where the thread consists of a largely over the top build-up to a spoiler tag with a pun inside it.
On November 22nd 2013 user Gtarmetro created a thread entitled "I've Got Something Really Important To Tell You.".
The thread consisted of the user building-up to something extremely important and urgent, only to have a spoiler tag with the phrase "The garbage man is down in the dumps today."
Further adaptations and general consensus.
There has only been one other thread so far, by the user StreetLights. This thread had a copy/paste title and content, apart from the spoiler tag, which had a photoshopped picture of a knife with the state of connecticut as the blade, and a caption saying "I will connecticut you"
This is the first adaptation of this thread to contain a visual pun.