A "Frosticon" is a pixellated 50x50 animated image created by Frosti that depicts a member's persona, usually for use as an avatar. The total sum of all Frosticons is informally known as Frosti's Icon Army.
On June 7, Frosti opened up requests for Frosticons to the entire site. She was promptly flooded by requests from members of every group on Route 50: staff, veterans, artists, roleplayers, visitors from dA, frequenters, infrequenters, and- most startlingly- random newbies. Some members chose not to use their icons as avatars.
As one can see in the image provided, a Frosticon contains the owner's abbreviated username (or full username if there is space), and the member's persona sitting on the ground with their knees up. While Frosti does not create icons with non-human personas, many icons incorporated elements of the member's Pokesona. Often times, this would prompt the member to alter their persona to match the icon.
For the most part, Frosti attempts to make the numbers of left-facing icons and right-facing icons match.