No Nut November could cause mental harm, physical harm and rumours (false ones) being spread.
participants could feel stress, guilt, pressure while participating.
besides, NNN has no medical basis.
So the risk of getting prostate cancer, blood stream issues or DNA damage to sperm would not be rational to risk.
It could be fun or cool to try out once, but if you treat it as a tradition or a long trend, it could possibly build up certain aspects of problems involving medical health, mental health and knowledge.
it should be treated as something satire, not something to actually participate in. if you do, it is not rational and a little bit of a risk to take for low rewards.