https://restoringhopebhm.com/blog/wilt-chamberlain-and-the-g...
By contrast, underhand free throw shooting is legal in the NBA and it is very effective. But it is seen as unmasculine rather than cheating. Players would apparently rather lose than be seen doing it.
Not just underhand, two hands between the legs
I think you can still cheat without doing something that is explicitly against the rules, by going against the established social contract of whatever league you play in.