Ask them to come round to the front door incase the neigbourhood watch thought they were burglars...then I'd ask them for a cure for cancer so I could market it and become a millionaire.
well if it was a sexy 3 breasted, 4 bum cheeked 3 handed 2 headed female alien id show her my room and tell her its the embassy of earth and show her how we great new visators NUDGE NUDGE NUDGE if you get my flow hehehehehehehehehehehe
I'd say "Now You look here, I wouldn't allow hippies in tents on My lawn, and I certainly won't allow You, kindly clear off before I set the dogs on You".