Sense of to exist, be present is attested from c.1300. Meaning to pay for as a treat is from 1821. Phrase stands to reason (1620) is from earlier stands (is constant) with reason. Phrase stand pat is originally from poker (1882); stand down in.
In Expert Mode, Wall of Flesh is seen to be significantly faster than his prior speed, posing map navigating harder as the players are demanded to plan out their routes fasters. In addition, getting pulled by his tongue will inflict additional damage to the player, possibly killing a weakened player.
If the player attempts to get behind the Wall of Flesh by any means, it will use a long tongue with a very far range to pull the player in front of it again, inflicting The Tongue debuff. While The Tongue debuff is in effect, the player cannot move or use items, and will likely take a large amount of damage as a result.