Fan name for the villager NPCs in Minecraft.
The name "Testificate" was originally seen as the name hovering above the villager NPCs during their initial release in Beta 1.9 Pre-release 1. The name hovered above there heads in a similar fashion to player names in multiplayer.
While the name was removed in Beta 1.9 Pre-release 2, the name stuck as a fan name thanks in part to Yogscast and the community as a whole.
I built my own house next to a NPC village and had an infestation of testificates in my building.