Onyxx was extremely happy that this water wasn't very cold. Those situations never ended well. No matter how cold it actually was, if a guy ever has to say "it's cold!" as an explanation, he will not be believed. It was a universal law, at least according to TV. At the same time, the water was cold enough to ensure no embarrassing "saluting the flag" moments.
In short, this lake was perfect. "Okay, okay, so maybe jumping over the lake wasn't the best idea," he laughed when she popped up to the surface. "But it was better than the time I fired myself from a giant slingshot."