A dark eldar character generates a pain token each time a living creature is stunned close to them and can also take takedown at 1st level.
With these two facts, a dark eldar could setup in its quarters a range of adorable space puppies (preferably with low toughness) and then proceed to punch (takedown) each of them in turn. The attack does no damage, but is likely to stun them and so grant a pain token. Assuming there is enough time at the start of each session, the dark eldar could amass thousands of pain tokens (usable as fate point rerolls) every game.
I know that obviously the GM can rule against this or put a cap in place, but is there anything in the rules that actually stops this?