I was trying to explain something rather complicated to someone at work, involving the way a lot of objects call each other in a particular order, and why. A cow orker walked up behind us and asked "Would it be OK for me to interrupt and ask a quick question?"

Immersed many stack-frames deep in code, where precise questions have precise answers, I forgot that it's impolite at that point to say "no", and continue explaining.

I think perhaps he was a trifle taken aback. Sorry Neville. :)