Lucas rits hiz furst sentins

Lucas was busy this afternoon at his arts and crafts table. I peeked over to see what he was doing, but was told not to look because it was a surprise.

After about 15 minutes, he showed me this.What is it? It's the first time he wrote out a complete sentence on his own.
What does it say? Once he told me, it all made perfect sense

Line 1: Pupcen
Line 2: Jaclatrn

The sentence is written off in the right margin and down below: Des es Lucas pectr uv u pupcen (hint he pronounces "th" more like a "d" or "t")

Priddee dam kul, donchu tenk?