Oh, you got mistaken for mother and daughter, huh.Do I look that old!!When the hell did I give birth to your little sister!!Hey, Kyon, listen!Haruhi had a day off, so she went shopping with my little sister.The problem is the employee from the shop I just went to!What's up with the scary face? Did my sister do anything to you?I'm already good friends with your sister!"Hey, mother, mother!"... is how she called me!Second personYou said it yourself that I was your baby. So I'd say, after giving birth to me.
Referencing this comic