Laughter

Riddle: What word is a fun word, until you add one letter and it becomes a terrible word that no one wants to happen?

Answer: Laughter: If you add an 'S' to the begging of laughter it becomes slaughter.

Source: https://www.riddles.com/5485

What word is a fun word, until you add one letter and it becomes a terrible word that no one wants to happen? — laughter by Riley Smith v1.

Riddle: What word is a fun word, until you add one letter and it becomes a terrible word that no one wants to happen? Answer: <a href="https://www.riddles.com/funny-riddles"><strong>Laughter</strong></a>: If you add an 'S' to the begging of laughter it becomes slaughter. — by Riley Smith v2.