Captain America star Hayley Atwell had an awkward end to her teens when her dad insisted on taking her to a Native American sweat lodge.

The British actress' Kansas-native father was obsessed with the history of Indian tribes while she was growing up, and when he got the opportunity to join elders at an authentic sweat lodge gathering, he invited his 17-year-old daughter to join him.

Atwell was up for the steamy spirit-chasing adventure at first, until she realised she would be sitting in a tent in her underwear surrounded by a group of naked, sweaty men.

She recalled the experience during a chat with U.S. Tv host Jimmy Kimmel on Tuesday (06Jan15), explaining, "It's like a sauna and it's really, really hot. There's 30 or 40 grown human beings... and everyone's naked, apart from me - I was 17.

"When we started the chants, the leader just said, 'If you wanna pee, just pee', so I spent the whole time just going, 'Please don't pee on me, please don't pee on me' - that was my chant.

"It was so hot and sweaty in there, they could have. I had no idea... Poor me."