Please do not wrestle with the child. Someone could get hurt - if not today, some other day when the child has a play date or goes to pre-school and starts wrestling with the other children.
Watch the rain and talk about it. Make up a story about the rain and write it down. Let the child draw pictures to illustrate the story. Not a big deal if the drawings are mostly scribbles; that's pre-writing.
Build a blanket tent and pretend to be camping. Write down a story about camping (can you tell I work in early education?).
Look through magazines or catalogs or the newspaper and find letters, then things that start with that letter.