Rachel McAdams ''slept with a Swiss Army Knife'' in Costa Rica.

The 36-year-old actress has confessed she was ''terrified and lonely'' when men were banging on her door all night as she went travelling alone in Costa Rica, after she'd finished filming 'Mean Girls' in 2004.

Rachel said: ''I was kind of stupid. I got off the flight to Costa Rica and got on a little four-seater Cessna plane and was dropped in the middle of the rainforest as the rain was pelting down. I got in a cab with no doors and asked the driver to take me to this hotel, and he told me in broken English it had burned down, so I wound up in a place costing five dollars a night.

''There was a cold shower and guys pounding on my door all night. I slept with my Swiss Army Knife in my hand, thinking: 'I'm going home tomorrow!'...I was terrified and lonely.''

Despite having a horrible experience, the 'Southpaw' star went on to insist she would travel alone ''all over again'', and do it exactly the same way, as she thinks it gave her life experience and survival skills.

She told Stylist magazine: ''I think it gave me a bit of chutzpah and ended up being one of the best things I've ever done. It taught me I could survive on very little too.

''I would do it that way all over again, it was life-changing. You get to prove to yourself what you're made of.''