Viral videos come and go in a flash, and there were probably a fair few who were hoping that YouTube sensation Rebecca Black would be limited to only 15 minutes of fame.

But Black — whose song “Friday” is the most-hated video on YouTube with 1.8 million dislikes — has some unusual staying power. According to YouTube’s Trends blog, since the song went viral around March 13, searches for the video have spiked every single Friday.

Why is this song sticking around for so long? YouTube has two theories.

For one, the song is an earworm. It gets stuck in your head, which may compel you to listen to it again and again. You know, just in case you can’t remember what order the days of the week go in.

The other reason YouTube offers for the song’s unusually long life is that it’s so easy to parody. A search for “Rebecca Black parody” pulls up over 4,500 results, about 1,000 of which are from this week alone.

Here is the original song as well as an epic parody from Stephen Colbert, Jimmy Fallon, The Roots and Taylor Hicks. (They did it to thank Fallon’s viewers for raising $26,000 for Donors Choose.):

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