You might think that would be cause for another round of torture and a repeat photo shoot, but remember how isolated North Korea was (and still is). When the Americans told their captors that it was a Hawaiian symbol for good luck, they bought it. The prisoners are being so cooperative, they're throwing up friendly hand gestures!
The photos ended up being published in Time, iconic symbols of defiance under duress. Unfortunately, publication meant North Korea was finally in on the joke, and that resulted in even worse abuse. This did not dampen the men's enthusiasm for mocking their captors. After a release was negotiated, they insisted the captive commander record a message thinking them. He did as he was told, but also carefully chose the word "paean" from a Korean-American dictionary in lieu of the word "thanks." The meaning was the same, but the pronunciation was "pee on." Which meant that as the soldiers were handed back to U.S. forces, the loudspeakers in North Korea were proudly blaring word of how the American commander wanted to pee on their leader.
Spoiler: This is not the last piss-related prank on this list.