Possible meanings are 1) Samson is so thirsty he could literally die. Alternate translation: "But now I will die of thirst and my body will fall into ... uncircumcised." or 2) Samson exaggerates how thirsty he is by asking if he will die of thirst. Alternate translation: "But now will you allow me to become so weak from my thirst that I fall into ... uncircumcised?" (See: [[rc://en/ta/man/jit/figs-hyperbole]])
The phrase "fall into the hands" means to be captured. "Those who are uncircumcised" refers to the Philistines and with the word "uncircumcised" emphasizing that they do not worship Yahweh. Alternate translation: "be captured by those godless Philistines" (See: [[rc://en/ta/man/jit/figs-idiom]])