I find it rather embarassing when something like this happens:
_xxx_ (phone rings): "Hello?"
Girl: "Hi!"
_xxx_: "Hi! Who's there?"
Girl: "It's me, Anna!"
_xxx_: "Oh, hi! Ahem, which one?"
Girl: *click*...
Of course you always know at least 5 girls named Anna with no memorable surname...
_xxx_ (phone rings): "Hello?"
Girl: "Hi!"
_xxx_: "Hi! Who's there?"
Girl: "It's me, Anna!"
_xxx_: "Oh, hi! Ahem, which one?"
Girl: *click*...
Of course you always know at least 5 girls named Anna with no memorable surname...