klin se klinom izbija

1. a problem is cured with more of what caused it; one nail drives out another; fight fire with fire
   Ostavila te je? Klin se klinom izbija, nađi novu devojku. — She left you? Find someone new to help you get over her.
   Boli te glava od sinoć? Klin se klinom izbija. — Head hurting after last night? Hair of the dog.

Often said jokingly about a new romance after a breakup or about curing a hangover with a drink.