Bin bags stuffed with Christmas waste could attract unwelcome attention from the UK's burgeoning rat population, Keep Britain Tidy has warned.
Rats can transmit a deadly disease to humans
The environmental group said rodents enjoy the festive period as much as humans - particularly the leftovers.
The group said there would also be more rubbish for the rats on High Streets because cleaners are also on holiday.
It has put up posters showing rats with the line "we're getting closer" to tell people to help reduce rubbish.
Keep Britain Tidy said there had been a staggering growth in the number of rats.
It estimates there is one rat per human in the UK - and that there will be more if we keep feeding them.
Spokesman Peter Gibson said the rat population would be making the most of the Christmas glut of leftovers - both outside people's homes and near takeaways.
"Expect rodents to make their way out of the sewers and the shadows to dine out on kebabs, pizzas, chips and burger louts leave behind," he added.
Rats can pass on to humans a potentially deadly disease, leptospirosis, through urine, droppings and bites.
The rat population is estimated to have increased by one-third since 1998, with Scotland and the North West among the worst affected areas.
Facts about rats
A pair can produce a colony of 2,000 per year
Females are pregnant for only three weeks
The average life span is 18 months
The average length is 27cm
They can chew through electric cables and cause fires
The Keep Britain Tidy group suggests avoid using paper plates and cups, buying drinks in large containers rather than small cans and bottles, trying to recycle where possible and make use of dumps.
"We have also talked to councils to try and get them to do more bin collections over Christmas - and some, especially in urban areas, have responded to it," Mr Gibson told BBC News.
Some 60% of councils are organising extra bin collections on 28 and 29 December, and about 4% will do the rounds on Christmas Eve.
But for those who live in areas where no special provisions have been made, rubbish might be lying around for as long as two weeks before it gets collected on Monday, 3 January.