Can you loose weight doing this?

My friend told she lost weight by sitting in her car with the windows rolled up in the sun and she had a 12 pack of ice waters and she sat in the car and sweated alot to where all her cloths was soaking wet but she kept drinkin water and she even snacked on wheat crackers so she said she felt good after she got out and took a shower and she lost like 10pounds in like 4 days doing this. so is this healthy or is so crazy. lol