"Oh Shit" moments...

Looking back at my chainslip moment when accelerating from a trackstand, I have come to the conclusion it wasn't a chainslip (as my tension is fine), but it was actually wheelspin which made me poo my shorts. Is this possible? Has it actually happened to anybody?

It's happened to me but only in the wet or snow.

My best bet is that you had a lockring and cog slip or something in the BB worth checking out.