When the roar happened, Dean didn't seem to flinch at all. His confusion was met with satisfaction. This wasn't a Tarrasque or a anything near it. Dean didn't even begin to go for his hammer, but, that was mostly because he trusted Kat's word than anything else.
"Oh, okay!" Dean understood as he spoke out his usually catchphrase. If the T-Rex was trying to intimidate him, it would be a useless effect. Instead, he just 'smiled' and waved at it. "Hello! Dean is Dean!" His 'smile' grew wider as he waved to the T-Rex as he had done to so many others before. His moved down to Kat. "Is Big Lizard Dean's friend?"