I remember seeing this as a kid, probably on TV in 80s or early 90s.
I seem to remember some humour and sabotaging one another's survival attempts. I definitely remember a scene with one of them urinating on another and wakening them up. Really, that's about it!
Is this Hell in the Pacific (1968), starring Lee Marvin and Toshiro Mifune...?
During World War II, an American pilot and a marooned Japanese navy captain are deserted on a small uninhabited island in the Pacific Ocean. There, they must cease their hostility and cooperate if they want to survive, but will they?
The Wikipedia page mentions a part about the American soldier urinating on the Japanese soldier from a cliff above him.
The next day, the American tries to steal more water for his canteen, but is caught and falls on the reservoir, destroying it. The American continues to torment the Japanese, destroying his fish trap, stealing his food, ringing his canteen like a bell, and throwing loose bullets on his fire pit. After urinating on the Japanese from the cliff above, the American and Japanese prepare to confront each other, but the American collapses from dehydration and is caught; the Japanese binds his arms to a log and makes him walk back and forth in the sand. Eventually, the American escapes and binds the Japanese to the log for the same punishment. After getting frustrated with their language barrier and the Japanese's use of resources, the American cuts the Japanese loose and tasks him with cooking; they continue to antagonize each other, but share chores and resources and stop trying to harm each other.
