Does he find Mark ridiculous or something?

Because Mark was being rude.

They were having a conversation about what they have learnt about themselves in there. Mark went on and on about what he had learnt, the moment Christopher starts to speak about what he's learnt Mark changes the subject to spiders then walks off.

Quite. Mark had stopped listening. Also, I'm not sure Christopher always has control over his 'face-pulling'.

Exactly. Mark was a complete and utter a**e towards Christopher. He was always dismissive of him. Like the time he told him to go into his own bed after calling him over the night before and snogging him.

Even on eviction night he rejected his kiss good bye because of his make up or whatever. "Mind my faceeee Cwistopherrrr" I know what I'd like to do to that face, but that's another story lol.

Mark used the spider as an excuse to make a quick exit. He was done talking about himself, couldn't be arsed listening to Christopher and Christopher knew it.

exactly, mark spouted on about himself, as soon as Christopher started to explain his feelings mark was more interested in the spider, same as always.."refreshments" comment etc- Mark wanted to get his voice heard for the sake of votes viewers..or he wanted to sway Christopher into agreeing with what mark thought, ...he had no interest in a conversation, or interest in Christopher's replies- could see it in his eyes

Christopher may end up lower placed because of his association with Mark. He should have kept more of a distance between them.

This. To be fair though, Christopher goes around and around a bit before he actually gets to his point.

True. I don't have much patience myself. But I was cringing at how obvious he made it. At least be subtle, Mark.

I thought that that was really unkind by Mark

We will never know.

"An actor's a guy who, if you ain't talking about him, he ain't listening." - Marlon Brando.