tearjerker

It is used to express sadness and sympathy over an event. This event doesn't have to be big it could simply be that a small thing happened and to express your sadness you exclaim "what a tearjerker" While some people may not understand or accept "tearjerker" as a real word it is.

Adam told Adelaide that he did not like FEVER 333's new album
Adelaide replied with "That's a tearjerker!"
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Quincy, the dog, ran away and Quincy's adaptive parents said "Quincy running away is suc a tearjerker."