3/23 is Hot Sandwich Day!It feels like something's pushing it in...Push, pushA little prank by Komeiji Koishi.A day established for cooking sandwiches in different recipes!
A previous commemorative day is Sandwich Day which is on March 13th. That day was established because the word sandwich (pronounced sandoicchi in Japanese) contains the numbers 3 (san) and 1 (ichi). And then, when the date March 13th is written as 3/13, you have the number 1 "sandwiched" between two 3s.
As for Hot Sandwich Day, the SFX for cooking something is juu, which itself can be read to be the number 10. And so if we "cook" Sandwich Day by adding 10 to March 13th, we get March 23rd. Thus, we get Hot Sandwich Day, a day distinct from Sandwich Day as it focuses on sandwich recipes where the sandwich is heated in some way.