You should probably say Hi back to him, before he does something unimaginable.
That's a Jerusalem Artichoke. I don't know why.
I know I didn't buy it.
I'm expecting a summons of some sort regarding its deployment in whatever skulduggery he is planning.
Whatever kind of gremlin you might be, it's OK to say "hi" - to a friend, to a random stranger... if a little kid waves, wave back at them. Not enough people take the time.
Happy Hi Day.