In PSO, today, I ...

[NetNomad]

They can accidentally kill each other with their under-ground "spike" attack; this tends to happen if two slimes do this attack at the same time, and one attacks the other... or if the "spike" comes out underneath another slime. Unfortunately, they tend to be able to kill each other with one hit (even though it only does 283 damage, which is less HP than a Pofuilly Slime has, which makes no sense). The slimes DO reappear after piping (because you start with the original 2 again), but from what I heard this might be like the Canune "trick" - you can pipe again so the Canune will reappear, but it can't drop you anything anymore...