A Coopersburg, Lehigh County man is known for doing things big but his latest surprise really takes the cake.

It's a huge, brightly-lit way of saying "thank you" to someone he calls his guardian angel.

These are pictures of Karen Heilman and Dennis DeKrane.

The couple has traveled to St. Martin seven times and for 15 years they have been by each other's side.

One night, back in January, Dennis was suffering from stomach pain and at Karen's urging they went to the emergency room.

Doctors at Lehigh Valley Hospital treated the stomach pain, but call it a woman's intuition. Karen felt more was wrong.

"They offered a CAT scan and I said yeah I think we should do a little further testing," said Heilman.

"Karen always has that second sense," added DeKrane.

On January 24, Dennis was diagnosed with non-Hodgkin's Lymphoma.

"Going through my mind was if something happens to me I won't see her anymore, I won't see my family anymore," said DeKrane.

Dennis went through nine months of therapy.

The time was a little tough for Karen, who is also a nurse for the Lehigh Valley Health Network.

"It's so hard for the patient," added Heilman. "You get to walk on the other side of the fence."

After successful treatment, Dennis found a unique way to say thank you.

"I wanted to surprise her," said DeKrane. "I think I really shocked her."

Dennis got a billboard on Route 309 south by Lehigh Street.

Lamar Advertising decided to donate six days of time after hearing their story.

"Could have blown me over with a feather," said Heilman. "I said a what? They said yeah you just happen to be recognized. A billboard over there."

Dennis DeKrane still goes in for routine tests to monitor his condition.

He never missed work during treatment, and even went fishing with his grandchildren.

And he didn't miss out on saying thank you in a big way.

"She's my best friend, she's my lover," said DeKrane. "I just had to tell everybody what I feel about her."