What does it mean when a guy sneaks up behind you and pokes you in the waste?

Then looks at you out of the corner of his eye and smiles as he keeps walking...

The guy I like did this to me the other day. That's why I'm curious...he also smiles a lot, remembers little things I tell him, shares about his family, gets jealous when I talk to other guys, notices changes in my moods, says sweet things to me, leans in when we talk...stuff like that.
What does it mean when a guy sneaks up behind you and pokes you in the waste?
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