hello stranger
US /həˈloʊ ˈstreɪn.dʒər/
UK /həˈloʊ ˈstreɪn.dʒər/

1.
a friendly greeting used when you meet someone you know but haven't seen for a long time
:
•
Oh, hello stranger! I haven't seen you in ages.
•
When she walked into the party, her old friend exclaimed, "Well, hello stranger!"