Mom: Are you seriously gonna die?
Me: No. Don't worry. Suicide is the last thing I'll do.
Mom: Are you seriously gonna die?
Me: No. Don't worry. Suicide is the last thing I'll do.
The humor comes from a morbid twist of words. The person isn't stating they won't commit suicide, but instead, they're saying it'll be the very last thing they ever do, which would be the case if they were to die by suicide.