I don’t think he said it. He seemed to be in complete control of what he was saying. It wasn’t an exclamation said without thinking. I doubt that he’d say it in that situation.
So what do you think he did say? The sentence definitely started with "I gotta get my...". What followed was certainly some word that started with "sh..". Any suggestions as to what it might have been if not the one that's being suggested?
BTW, anyone who uses such language on a regular basis wouldn't necessarily say it with any exclamation. Notice how teenagers (and many adults) use the F-word as a universal adjective without any particular exclamation. It's just part of their everyday vocabulary.