Pete is:

Learning about tense:
"Me try go potty, but me do ... no ... umm ... me don't did it!"

Speaking british english, thanks to Thomas the Tank Engine:
"Must get off bed"
"Me eat bit sandwich"

Learning the many uses of precise language:
"My mommy play trains" - This was in response to me saying that I couldn't play trains with him last night because I had to do some cleaning. It was said quietly, almost to himself, and had a guilt-trip tone of "Mom plays trains with me during the day, even when she's busy..."

"My tummy almost hurt" - This was in response to our explaning to Pete that he shouldn't lie about pain. After having been sick and realizing that he gets whatever he wants when he's sick, he occassionally tries to get out of things by claiming that things hurt (his tummy, his feet, his legs).