OnGob

Short for "on goblin" and in the vein of "On God", OnGob is an expression meant to emphasize the veracity of a claim, much like "I swear on my mother's grave". Its spiritual and etymological underpinnings lie with the phrase "goblin mode", and when swearing "OnGob", one could be said to swear with all the seriousness of a thing experiencing "goblin mode".