Police are investigating an incident at McDonald’s on Ullswater Road in Penrith.
The incident occurred at 1:30am on Sunday 19 May.
A Cumbria Police spokesman said: “A young male has approached motorists and asked them to get him some food from the drive-through.
“When refused he has become abusive and threatened to assault a 22-year-old motorist, causing him to fear that he was about to be seriously assaulted.
“The suspect was riding around the area on a black mountain bike.”
Police are appealing for anyone with information to contact PC1728 Nigel Hamblin on 101 or call Crimestoppers on 0800 555 111.