mood killer

‘something (for example, a situation or an event), that causes, someone to get sad’; ‘someone, who ruins the mood for other people.’

The expression in polish would be literally translated as: „zabójca nastroju”

In youth language the phrase mood and its polish diminutive moodzik could also be understood as well-being’.

Examples:

1. (…) I keep telling her, the american one, and then she says, its all sold out. Its all sold out! It was such a mood killer! [a teenager telling his friends about ordering food](overheard)
2. – There’s no bigger mood killer than when your computer crashes and you lose a save. [a conversation held between friends] (overheard)
3. running out of tide pods can be a real mood killer! https://www.instagram.com/grace_thebeagle/reel/C-7xJRIIZzu/