Leetmas is the time of year at Video Game High School where all holidays are celebrated at once. This include Christmas, Pi Day, Easter, Thanksgiving, Saint Patricks Day, Halloween, Independence Day, etc. This holiday is shown in Episode 5 of Season 2. The day it is celebrated is on September 17th according to the VGHS calendar
How Leetmas began-
Leetmas started a year or so before BrianD joined Video Game High School. In the beginning of the episode, you can here the ending of the story on the radio while BrianD is cooking. The story, by context clues, is that Calhoun, grumpy and tired of dealing with students' holidays, tried getting rid of all holiday celebrations. The students fought back and the battle of holidays ended with a compromise that is Leetmas. With this compromise, the students can still celebrate holidays and Calhoun only has to deal with it for one day.