I'm not sure if this affects just bids of the opponent but when ever he bids sixes and is lying you always lose a dice when challenging the opponent.

Like in one example, he bid atleast three 6's I challenged the the bid and lost a dice. When he clearly only had 2 Six Dice and not a single 1 sided dice.

I believe this only seems to affect when bids of sixes are in play.

Disregard...I am a dork and forgot bluff takes into account your dice as well xD