You might get a better response by providing an example of one such counter-intuitive argument that you find good.
I guess the birthday paradox is one such example (https://en.wikipedia.org/wiki/Birthday_problem) but if you've taken a course in probability theory then it doesn't really seem counter-intuitive.
There's quite a few veridical paradoxes in probability theory
But haha I was just thinking about math stuff at all. More like sociological, biological, systems, anything!