Today's comic comes to you from Saturday Morning Breakfast Cereal's very own Zach Weiner(smith). Blame him if you need to.
In all honesty, though, there are lots of examples of 'rocks' that would get spontaneously warmer than the surroundings via chemical reactions. Yeah, if there's not a chemical reaction involved (or radioactive decay, I guess,) then sure the 'Jesus' character is violating one of the major principles of thermodynamics.
