Blase lottery winners have left their life-changing tickets in a series of silly places, Camelot said as it publicised £9 million worth of unclaimed prizes.
Players have stashed their winning slips in such places as under the dog's basket; inside a tin of cat treats; in the car sun visor, and one winner stored his in his secretary's make-up bag.
The National Lottery was launching National Back of the Sofa Week to encourage players to rummage between the cushions for missing tickets.
A giant lottery-themed couch will be visiting the streets of Plymouth, Leeds, Stoke, Blackburn and Oxfordshire where jackpot prizes of up to £1 million are still waiting to be claimed in each area.
"The sofa is usually where families across the country gather in the evening to watch a bit of TV or just relax, so there is no excuse not to have a quick look," said a Lotto spokesman.
"It only takes a minute to delve between the cushions and you never know what you might find.
"From our experience with unclaimed prizes, the sofa isn't the only hiding place where players have found their winning tickets.
"Buried in coat pockets, in cupboards and even down the back of the kitchen drawer could be your chance to claim a life-changing amount of money."
Currently there are six millionaires who have not claimed their prizes - with the EuroMillions Millionaire Raffle tickets bought in South Lanarkshire, Stoke on Trent, Ealing in west London, Blackburn, Leeds and Plymouth.