When someone says something that's supposed to be funny but really isn't, or alternatively when someone takes a joke a stage too far, and makes it un-funny. Someone else has to then announce it as a Russian Roulette Moment
Some people's entire lives are like one huge Russian Roulette Moment
, ie. everything they say is supposed to be funny but never is
Becky: "It's like Russian Roulette
...who's gonna gan? Gan, gan!"
Daniel: "Excuse me everyone, can I please have a moment of your time? I just have a small announcement to make, I'm dying *serious face*
Becky and Ross: "Russian Roulette Moment