|Olivia Wilde and Jason Sudeikis|
The couple was on the Caribbean for a vacation and got caught up in danger because of their competitive nature.
The 28-year-old actress has been dating Jason, 36, for six months and revealed they had a kayaking mishap and potential jellyfish disaster during their first holiday.
She said on 'The Late Show With David Letterman': " He was really good at getting in his kayak right away, but I got bashed in the knees. . .I was like, 'Babe, you're so good.' And he's like, 'Honey, I'm an athlete, so. . .'"
"I was trying really hard to be in front since he made that athlete comment, so I was really pushing through. It got a little too treacherous and I turned around and Jason was gone. Gone! I saw an upside down kayak . . . and suddenly I realised that I was about to go over.
They soon "resurfaced and we were rescued by a team of fisherman."
The 'People Like Us' star added: "On my way back in, I got stung by a swarm of jellyfish. . . I was covered in welts. I was like, 'Babe, you have to. It's the only way. You have to swim through the swarm of jellyfish.'"
"We were fighting for honor. It got really serious. I had to go and get the same rescue team to come back with a kayak to get him out of the water."