Who are those ppl the one holding a hamburger together

The pink haired girl with glasses is Hinata Miyakawa. She works at a dojin shop, is an otaku, and lives in relative poverty because she spends all her cash on manga.
The blue haired loli is Hikage Miyakawa, Hinata's kid sister. She's in elementary school, hates okatu because her sister wastes all their money on manga, and wants to grow up fast so that she can get a job of her own to support herself.
The reason you probably didn't know them is because they're only primary seen in the manga and games, although they did make a cameo appearence in episode 16.
Try this Wikipedia link for a little more info: http://en.wikipedia.org/wiki/List_of_Lucky_Star_characters#Hinata_Miyakawa

I hope that helped Rima!