If you've seen Red vs. Blue, yo might want to take notes from Caboose.
If on fire: 'Oh, god! I'm burning! That's much worse than other things burning!'
If the fire is not put out: 'Oh, god! Why does it keep chasing me!'
If talking about someone that confused him: 'Yeah, he did seem pretty confused. Or was he confusing? I forget which one...'
Upon being told he has no idea about something: 'Yes. Nobody has any idea.'
If the villain is evil because they are unhappy: 'I will eat your unhappiness!'
Stuff like that.
In fact, even some of the other characters have some good ones.
If someone doesn't speak common: 'People learn common all the time! It aren't that hard.'