The ornamental design for one piece body thong, as shown.
FIG. 1 is a front perspective view of a one piece body thong showing my new
design is use, the partial broken line showing of a female figure being
for illustrative purposes only and forms no part of the claimed design;
FIG. 2 is a rear perspective view thereof; and
FIG. 3 is a left side perspective view thereof, the right side being a
mirror image.