The Bath Chronicle reports that Reece Coombs was having dinner with his girlfriend, when the rat decided his chips looked delicious.
"I thought: 'that rat has some serious confidence'. I didn't know whether to laugh or cry," Coombs told the Chronicle.
According to his girlfriend, Lucy Wrenn, it wasn't a small rat.
"I would say the rat was just short of a pint glass - it was really big," she said.
The pub responded to the rat by closing down - and ushering its other customers out of the door for about half an hour before reopening.
They have since called in pest control to ensure the rat doesn't make a repeat appearance.
While Coombs has said he doesn't plan on eating at the pub in future, he will still be drinking there.