What's Ideas of March? I haven't been on Tumblr for a full year yet
March 15th is also known as the Ides of March in the Roman calendar, and what's celebrated is a very successful group project that took place back in 44BC in the Roman Empire. A group 60 senators conspired to assassinate Julius Caesar. However, all group projects have some people that skirt their responsabilities, that's why Caesar only had 23 stab wounds.
Because this is Tumblr, the death of the dictactor is celebrated every year with top quality memes and shitposts. It's a Tumblr Holiday.