The Event rpg was obtained during the 2014 Goblin Invasion event. It was obtained by speaking to either the Goblin Recruiter or the Guard Recruiter, depending whose side you joined. It was required to use this in order to make the goblins/guards attackable.
The Event rpg is unique in the sense that it is the only melee weapon to possess an attack speed of 7, the equivalent of Knives and Darts, and the Toxic Blowpipe. Because of this, it is commonly seen among lower level PvP builds especially among players with 1 attack where its attack speed out-performs other weapons of a similar tier like the Iron scimitar.
There is an option to 360NoScope-paint someone when you right click another player. Doing this will result in your character shooting out what looks like a huge ball of paint. There is a small chance that you will get a message saying "By some miracle you hit the target!" when you 360NoScope-paint someone.