Keltham taps himself with a truthspell, and Abadar's symbol flashes above his forehead.
"As my people define 'lying', the act of 'lying' means dishonesty, and doesn't include saying literally false statements as jokes, or teaching aids, or ways of 'trolling' people, if you don't expect them to end up persistently believing false things nor do you exploit their false beliefs to their own detriment during the bounded period they persist."
"I've never lied to anyone in Golarion."