Hate-meister is a derivitive of the know phrase "hate monger", but is used as a substitute to try and explain the severity of a hate monger to children.
guy 1: i wish i knew who the guy was, behind all those murders
Similar to many other 'meister' names, 'g meister' is most commonly used as a nickname of endearment with the 'g' often being the individual's initial.
Although, 'g meister' specifically, may also pay tribute to 'Game Master', (or even 'Dungeon Master', as Dungeons and Dragons refference) as the direct German translation for 'meister' is 'master'.
A fart meiser is defined as someone who is extremely self conscientious about their farts; therefore, they will hold in their farts even when it is dangerous to theirself and the ozone layer.
Have You Ever Heard Mark Fart?
No dude, he's a total fart meiser.