Gives a thrashing is an idiom which means to severely punish or reprimand someone. The two crossword solutions for this term are 'flails' and 'drubs'. Flails is a verb meaning to swing something around wildly, usually in an effort to hit something or someone. Drubs is a verb meaning to beat someone or something repeatedly. Therefore, both of these words can be used to describe the action of giving someone a thrashing.