Senku starts a ramen stand in hopes of winning over support for his kingdom of science, but some people are too principled to take such a bribe. Mentalist Asagiri Gen is not one of them.
It's a trick called the 
back palm or something.
.إنّها خدعة تسمّى بالكفّ الخلفي أو ما شابه
Diese Technik nennt sich
„Back Palm“ oder so ähnlich.
É um truque chamado de atrás 
da palma, ou coisa assim.