Nigawarai are a yokai (or monster from Japanese folklore) that appear as an ugly, hairy creature with horns. Dressed in dirty rags, their mouths are held in a forced smile. These creatures feed off ill-humour, forced amusement and uncomfortable laughter. In turn, they cause ill-will, disgust and arguments in people and the environments they inhabit. The name nigawarai translates as 'bitter smile"
Being a jew aside, they always have that permanent half smirk even when they speak, for example Rachel madcow