Fans, young and old, were happy to stand in line to join the party on Monday, when King Taco celebrated its 40th anniversary by offering 50-cent tacos, at all of its locations.

For the second straight year, the Mexican fast-food restaurant offered its signature tacos, which normally cost $1.29 plus tax, for 50 cents.

“Nobody is off today,” said Gabby Castro, supervisor at the Pico Rivera King Taco.

She doubled Monday’s staff to help with the onslaught of hungry customers.

A year ago, they prepared and sold about 16,000 tacos in a 12-hour period at the Castro’s store. This year, they expected to make more tacos since they will be offering them an additional two hours.

“We wanted to be prepared,” said restaurant manager Cecilia Hernandez.

On Sunday, staff prepared the onions, cilantro and salsa, that would go into the carne asada, chicken and carnitas tacos.

“People waited up to 2½ for their orders,” said Hector Beltran, a cook and server in Pico Rivera. “There were orders for 100 tacos at a time.”

Dozens of people packed the Baldwin Park restaurant at lunchtime on Monday, many of them ordering at least a dozen tacos at a time.

“We didn’t know it was a special day today,” said James Goodman of Commercial Refrigeration Specialists in Irwindale. Goodman had been waiting 40 minutes with a coworker from Northern California.

“They don’t have these up there so he comes down and loves to come here,” Goodman said.

In addition to the great discount, what could make people wait from 45 minutes to more than two hours?

“It’s the taste,” said Cirilo Soto, 52, of Montebello. “I had a craving for the tacos, so I came here, only to find out they were 50 cents. What a pleasant surprise.”

He and another customer, Sandy Garcia, also of Montebello, said the lure of the restaurant was more than just the great food.

“It’s been a tradition to come here since I was in high school,” Soto said. “It was open late after the football games.”

Garcia, who fed her three-year-old daughter, Jayleah, said she remembered coming to King Taco as a child.

“My mother brought me here, always for the carne asada tacos, so it became a family tradition,” she said.

Linda Maldonado and Liz Romero of La Puente eat at the Baldwin Park location a couple times a week, they said, and had ordered 11 carne asada tacos for lunch.

“The food is delicious,” Maldonado said. “It’s the best meat ever.”

The pair were two of only three people eating at the restaurant at 12:45 p.m., because all of the other tables were full of patrons waiting for their order.

There are 22 King Taco locations in the Southern California, including the El Monte, Pasadena Los Angeles, Bellflower, Lynwood, Ontario and Fontana.

The original restaurant is on Cypress Avenue in Los Angeles.