Possibly, what hurts/irks most, is not that your opponent borrows your dice, because he forgot his, but it's that you lend him your 'crappy' dice, that you seldom use, cuz they suck; But that they then start doling out 5s and 6s (for his ork shooting

) like condoms at a Free Clinic.
*That* is the time to really whinebitchpissandmoan.
For the
OP:
It sounds like you were already crushing him, and that your one bad throw was the barest of salve on his already gapingly wounded ego. And then you had the *
audacity* to take that away by complaining about it. Bad form, sir! Bad form, indeed.