Related Clues:

• Like a stick-in-the-mud
• A drag
• Too Puritan
• Not at all exciting
• Like a buzzkill
• A real drag
• Devoid of joy
• Completely joyless
• Like a Debbie Downer
• Devoid of any pleasure
• "You're ___ at all!"
• A total drag
• ___ League (what NFL stands for, according to people who think its rules are joyless)