Well, there i was, full iron armour, a freshly made diamond pick, mining obsidian. Wishing nothing more than to beat the crap out of some pigmen. When, it happened.

Okay, lets go back before it happened, i was gloing through my mineshaft collecting the necessary ores and minerals to make some equipment, then i saw two white dots in the distance, i followed it, thinking they were miscoloured enderman eyes, then i found the obsidian, sitting there, near no lava or water.

Even earlier, i was harvesting my crops, hole and seeds in hand, then i saw what was clearly a zombie, in daylight, not burning. It ran away, i didn't follow it, but i saw it had white eyes...

Oh yes, what happened when i mined the obsidian?

Well, let's just say i did get to the nether.