Donacdum

Donacdum has two different definitions:
1: Don't Act Dumb is a line said by Houston, from the video game Payday 2. The community makes it sound like he is saying "Donacdum", and a Payday meme was created
2: A song created by Lord Simon Viklund, and voice actor and musician, mostly focusing on the soundtrack for Payday 2. While he worked with Overkill Studios, he created the song in the light of the communities reaction to Houstons voice line.

A quick rendering of telling someone to not make stupid actions and/or decisions in the current situation they got themselves into.

DONACDUM is a mondegreen of the line Don't act dumb in the game payday 2 said by the character Houston. the line eventually became so popular that it became part of a song in the official soundtrack of the game. the title of the song is the same as the line DONACDUM.