After some more thought, I recalled a few more euphemisms I am particularly fond of. From my astronomy/spaceflight hobby come the terms lithobraking (in the catastrophic sense) and rapid, unscheduled disassembly. Another great one, which I read online somewhere, is solipsistic omnicide.
I have never been particularly fond of slang, so I don't have much to contribute. The one example that comes to mind is how my brother and I always refer to marijuana as "FROGS."