From the RuneScape Wiki, the wiki for all things RuneScape

Diango

Release date	Unknown edit
Race	Human
Members NPC?	No
Quest NPC?	No
Location	Draynor Village
Sells items?	Yes
Skill requirement?	No
Quest requirement?	No
Gender	Male
Examine	He smells funny.
Notable features	Can return some holiday items if they are lost

Diango and his toy stall.

The holiday item return interface.

Diango's selection of toys.

Diango is a non-player character whom Jagex added to RuneScape on 1 April 2004, as part of an April Fools' joke. Players had been requesting horses in the game for a while, and were excited to find out that Diango was to be added to sell "horses" in his store (Diango's Toy Store) in Draynor Village. Fitting the part, Diango wears a cowboy hat, chaps and even boots with spurs on them. However, Diango actually sells toy horseys.

He was also part of a practical joke the next year, when he started selling "dragon plates": spinning plates with a picture of a dragon on them. These arrived on 4 April 2005 because, as Diango says, they were supposed to arrive on the 1st but thieves stole them because they mistook them for Dragon platebody armour.

On 1 April 2008, Diango started to sell Dragon Kites; not the dragon kite shields players had long been hoping for, but a red kite with a picture of a dragon that players may fly. After buying one for 100gp, players can wield the kite and have it float alongside them or choose the Fly option and fly the kite for a moment in a strong breeze.

Diango will return all non-tradeable holiday items to anyone who lost theirs or stored them in their house's toy box, as long as they originally received the items from the holiday event. He is occasionally involved in holiday events, such as the 2006 Hallowe'en event and the 2005 Christmas event.

A hidden update on 16 December 2008 allowed players to right-click on him to claim holiday items.

Diango's chathead and greeting.