Millions of Christmas jumpers will be worn once and then thrown away this year, sparking a warning on waste.
Environmental charity Hubbub found one in three people aged under-35 will buy a new Christmas jumper every year, because they are so cheap.
Survey respondents also admitted they didn’t want to be seen in the same one twice.
With the novelty jumpers now a firm part of the festive season, shoppers will spend £220m on them this year.
The charity has launched a Give a Knit campaign, to encourage people to jazz up their jumpers to wear again or to swap them with friends to have a new one to wear.
The “need for new” is harming the environment, as the Ellen MacArthur Foundation recently found with greenhouse emissions from the throwaway fashion market topping 1.2 billion tonnes a year.
Hubbub spokeswoman Sarah Divall said: “The Christmas jumper phenomenon is now a firm part of our Christmas celebrations in the UK and it has raised a lot of money for charity.
“However, it’s also the perfect opportunity to reflect on our addiction to fast fashion which is having a devastating impact on the environment.
“I’d urge people to think twice about whether they really need to buy a new jumper this year. Instead let’s dig out all those Christmas jumpers hiding away in wardrobes and swap with a friend or donate them to charity shops or even refashion something you already own.”