Police said a customer came up to the counter at the Jack in the Box just prior to 12:30 p.m. Monday and asked a worker for some ranch dip, Seattlepi.com reported Tuesday.
The man received two packets of dressing, but allegedly became angry when he was told a third packet would cost 25 cents.
Witnesses said the man loudly argued with the cashier about being overcharged and the worker gave him a third packet, but the man continued to yell.
A 68-year-old customer attempted to calm the man down, but the man allegedly pushed the customer to the ground and left the store.
The customer who was pushed did not sustain any serious injuries, police said.
The suspect left on a purple bicycle. Witnesses said he was mumbling something about a knife as he exited the restaurant.