It is what my character would do.

[Zombieneighbours]

Sooooo,

Caleb has managed to sum up why "It's what my character would do..." is stupid. He has done it really well several times.

I can't however remember in which episodes.

I am currently dealing with a fellow player who acts like a dick  at the table, and use his character as justification. It would be nice to share Caleb's explination with him.

So if any of you happen to know where I can find examples, that would be good.

[The Lost Carol]

I swear, this annoyed the piss out of me. I know the Caleb discussions you're asking about, but I can't for the life of me think of the episodes.

However, I remember Ross and Tom talking about it in a main show, specifically about how negative traits can backfire. Episode 111: And The Nat 20 Goes To…Acting in Game. The example is how hating werewolves can backfire in when you need the help of a werewolf, when killing the werewolf is 'what my character would do.'

http://slangdesign.com/rppr/2015/02/podcast-episode/rppr-episode-111-and-the-nat-20-goes-to-acting-in-games/ (starting @ 23:10)

Also of help would be the Ethical Concepts in games panel from last GenCon: if he just needs ways of being 'evil

http://slangdesign.com/rppr/2015/08/panel-discussion/panel-beyond-lawful-good-evil-ethical-concepts-in-rpgs-at-gen-con-2015/

[Mr. Purple]

I believe the incident that sparked the discussion was our first play of Base Raiders (aka the birth of Professor White.)  Caleb was handed a pregen character who was a recovering addict, and when he found the super-powered drug supply he claimed them all.  This super-powered addict became the super-powered dealer we all know and love.

Caleb's argument for the action was well-stated, but I feel he left a bit out of it.  He was wearing three hats at the time- character, player, and playtester/fellow designer.  His actions were not only in character, they were also an example of what a character could and would do; wearing that third hat, he helped to show a potential rough spot in the scenario.  Overall, 2 out of three hats supported his action.

[Zombieneighbours]

Thank guys, I shall re-listen to these suggestions. Hopefully, one of them is the one I am looking for. With any luck I can stop the foot burning!!!!

[Vivax]

To David's point about Caleb's actions as Dr. White, Caleb didn't just grab all the drugs he could, use them, sell them, or horde them. Caleb played into the character in such a way as to facilitate an interesting scene with Tom's character and transform them into the Foot-High Science Guy. It didn't stop play. It generated some funny dialog between Tom and Caleb, established personalities and gave Tom part of his origin story.

If you player's "What your character would do" is stopping play or the evolution of the narrative than you need to try to redirect them into making choices that work more like Caleb's choices. 

[Jace911]

As has been said, negative character traits should never stop the game, they should provide conflict to make the game more interesting.

In the case of "I hate werewolves", if the GM puts the party in a situation of needing to work with a werewolf to get what they want a mature player does not go "well I hate werewolves so I KILL HIM". A mature player says "we can work with him, but my character won't like it one bit", which can lead to a discussion about why that character is so unwilling to trust werewolves. That discussion then leads to introspection and reflection, which is absolutely essential to character development.