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.
The Wall of Flesh is a boss, it is summoned by throwing a Guide Voodoo Doll (dropped by Voodoo Demon)into lava in the underground while the Guide is alive. The Guide will get killed on spawn, after Wall of Flesh is killed the first time, the world will enter Hardmode, spawning new enemies, ores, and greatly increasing the difficulty.