The last problem in a series of problems that finally makes you give up, lose patience, or take action.

अंतिम बूँद जो सब्र का बांध तोड़ दे

English Usage: When she didn't answer his calls, it was the final straw for him.

Hindi Usage: जब उसने उसकी कॉल का जवाब नहीं दिया, तो उसका सब्र का बांध टूट गया।