I managed to jump out before the explosion, where I soon survive the landing because I landed in water.
The next user is instantly shattered
I use duct tape to heal myself.
By the way, "However, I am a plutonium-based lifeform, so when they light the fire for the cremation, I reach critical mass and explode, destroying everything within thirty kilometers in a nuclear explosion.": You're still dead.
I vaporize the next user (and disintegrate the resulting molecules into atoms then into plain quarks), put them in a bottle and send it out of the solar system on a path that will never take them near another planet.
But I have a giant knife in my hand and cut my way out of the cake
The next user is a Grambling State basketball fan who has vowed to commit suicide if Grambling State loses another. They are down by 100 points and there is 10 seconds left...
That situation is kind of messed up. We Americans take that very personally. (I don't know if you are a U.S. citizen, but it is just way too messed up for me to reply)
ON TOPIC:
The next user is about to explode randomly.
The explosion occurs, but it involves a single U-235 atom in my body undergoing spontaneous nuclear fission, thus I am not harmed as there is nowhere near enough energy to do any noticeable damage.
The next user is a snowball that teleported to the atmosphere of Jupiter.
Which is just how I like it. I obtain wood from an abandoned mineshaft to make tools with, ultimately making an IndustrialCraft UUM generator to make infinite supplies.
The next user is trapped in a Minecraft world made entirely of bedrock.