And many people decide to leave them on for a while as a part souvenir/part badge of honour ("Oh yeah, I’ve been at Glasto three times. No big deal.").
The more dedicated festival-goers tend to accumulate a decent amount over time, charting their summer from Body and Soul to Electric Picnic, getting grubbier and grubbier as the months and even years pass.
But just how gross are they? Very, according to this video.
Two Australian radio hosts, Veronica and Lewis, decided to have a microbiologist test out some old wristbands sent in by a listener - the oldest was from a festival back in 2009.
Using one worn by Veronica for just a few days as a control, the lab added samples from the bands to a petri dish full if agar to test for bacteria - and the results are not great.
Which isn’t really surprising considering how gross festivals themselves can be.
So yeah, maybe take it off fairly rapid next time.