"Hey, Veteran's Day. Take care of this guy. Of the people, by the people…"
Personification of Lincoln's Birthday.
Lincoln's Birthday gangs up with Washington's Birthday to take over Holiday High after Christmas and Halloween go missing. He apparently has a problem with Arbor Day's choice of footwear, and sics Veteran's Day on him.
The Presidents lose their place at the top of the heap when Christmas and Halloween show up and take over again as the most popular kids in school.
(If none of this seems to make any sense, blame the writers.)