How do Fergie and Josh Duhamel
's keep their relationship strong? Fishing, cooking and karaoke.
"We always do quirky romantic things," Fergie, 31, told PEOPLE Saturday at the 5th Annual Cadillac Super Bowl Grand Prix, where the singer, Duhamel, 34, and other stars raced go-karts for charity in Miami.
"It's not just Valentine's Day. Like we went to Cabo San Lucas, and we took a cooking class and we went fishing for marlin and mahi mahi."
And she's not the only one who can belt out a tune. "We sing karaoke. At his house, he has a karaoke machine," she said.
"Sometimes we'll sing really corny duets together when a couple of our friends are over. He does 'Total Eclipse of the Heart,' which is amazing. You've never seen anything like it. He gets into it. He's pretty good. He's better than you would think!"
Duhamel, who is about to wrap the fourth season of NBC's Las Vegas,
added that they've figured out how to avoid the pitfalls of a high-profile relationship.
"We just genuinely love each other," he said. "We stay out of the spotlight as much as we can. So many times people are too in the spotlight, which puts too much pressure on things."
That doesn't mean they don't pay attention to what the media is saying about them. Last week, Fergie denied reports
that they were getting married. "We get a kick out of it," Fergie told PEOPLE. "Every other week, we hear we're engaged."
At the go-kart race, Duhamel, last year's defending champion, was excited about taking on Fergie, who was racing for the first time.
"I'm looking forward to beating my girlfriend," he said. "She's been talking smack all week. She wants a trophy of her own."
"I'm just hoping my natural abilities will come into fruition during the race," Fergie joked. "We get a little competitive sometimes. We had a lasagna cook-off one time and basically I was the better bluffer. He won the contest because mine ended up soggy."
Unfortunately for the "Fergalicious" singer, she was defeated in the first round of the three-round race, which also included Nick Lachey, Queen Latifah, Paul Rudd, Terrence Howard, Venus Williams, Melina Kanakaredes and quarterback Matt Leinart. Duhamel made it to the final round, along with Lachey and TV personalities Leann Tweedon and Tony Potts.
(Tweedon won the race – and a check for $10,000, which she donated to the charity Wounded Warrior. Lachey donated his $5,000 second place prize to the Make-a-Wish Foundation and Potts gave his third-place prize of $2,000 to Haven Hills.)
Lachey was there without his girlfriend, Vanessa Minnillo.
"She bailed on me," he joked before the race. "She doesn't want to see me get thrown into a bail of hay."