A moment/event which is so unfortunate or tragic, due to which, even if a person commits suicide, it's completely understandable.
Tim: I was working on my essay since two hours straight, and I took a break for 'bout 2 minutes. That's when my mum walked in, and she thought, I was lurking this all time around! I
Fred: That's totally LSM: Legitimate Suicide Moment!
Fred: That's totally LSM: Legitimate Suicide Moment!
by Internet Human January 27, 2017