Lottery ticket
From Tardis Wiki, the free Doctor Who reference
A lottery ticket was purchased by the Tenth Doctor using a pound given to him by Geoff Noble. Through her mother and grandfather, he gave the ticket to Donna as a wedding present a few years after Geoff's death. When given the ticket, Donna considered it to be a cheap present, but remembers that the next lottery draw has a triple roll-over prize. She then stuffs the ticket in her dress for safekeeping. Both Wilf and Sylvia knew that the Doctor has made sure that it is the winning ticket, thus securing Donna’s financial future. (TV: The End of Time)