National nude day is on the 20th of April. This is the day where you said nudes to people and you feel comfortable doing it. If a person sends you this you have to send nudes or any kind.
The 6th of October, is a day where people must send nudes when asked upon. Your relationship with this person is irrelevant on National Nude Day. This is the only day of the year where best friends can send nudes with no questions asked or no awkwardness.