N. The other name for the second day of the week (assumeing you start from monday) Tuesday. Twosday is the day of the week where anything interesting happens. It may also be used as an excuse for doing things.
Twosday is a very flexiable word and is most used to discribe sexiual happenings. This is closely associated to the phrase "Only on Twosday"
1. Will you go to the dance with me? 2. Only on Twosday.