A New Jersey man was stunned to receive over 15,000 calls and messages wishing him a happy birthday after his sons played a hilarious prank on him.

Though Chris Ferry’s birthday was on March 16, he is still getting birthday messages days later after his sons put his name, photo, and phone number on a massive billboard. The billboard included the words, “Wish my dad happy birthday. Love. your sons.”

Chris recalled how puzzled he was when he picked up his phone to receive the first birthday wish.

“Saying ‘happy birthday.’ I said, ‘Who’s this?’ He said Nick. ‘Nick who?’ ‘You don’t know me.’ ‘How do you know it’s my birthday?’ ‘I saw it on a billboard,'” Chris said.

The billboard was funded by Chris’s sons, Mike and Chris, who both live in Florida. Mike said that they figured that a few local friends would think the billboard was funny, and that his dad would get a few calls. They never expected for the billboard to go viral and for him to get over 15,000 well wishes!

The prank was actually a continuation of a prank the boys had been playing on their dad since they were kids.

“They would always tell the waiter or waitresses that it’s my birthday, even though it wasn’t,” Chris said.

“It was fun until this morning, then I wanted to kill them, but I’m going with it,” Chris added. “I’m having a good time. Most of the messages have been … well two or three that were not nice.”

Chris is already cooking up a scheme to get even with the boys, but Mike said that they are ready for it.

“I would love to see him try,” Mike said. “I just want to say I love my dad. He always puts other people first, especially me and my brother.”