The gemara [Bava Metzia 46a - see there] understands the Mishna to be discussing this seemingly odd case of a person who is standing naked on the threshing floor and thus can't perfom a kinyan chalifin. The gemara asks - ואיכפל תנא לאשמעינן גברא ערטילאי דלית ליה כלום? - Did the Mishna trouble itself to tell us such a remote case of a person who is standing naked on the threshing floor?
Asked the Chebiner Rov: Why wasn't the gemara bothered by a different issue - to redeem Maaser Sheni [which is what the Mishna is discussing] one needs to make a bracha. How does one make a bracha while wearing what [unfortunately] many women in New York city "wear" [or better "don't wear"] in the summer?? [I like to be melamed zchus and call it "insomnia". They just forgot to get dressed.]
