Obachan's 1st Appearance?

Discuss everything Gaki no Tsukai here.
Does anyone know when she was first introduced in the show or in a Batsu game?

Now everytime they see her, they're like "Again !!", but before she was announced as a random old lady, so I'm wondering.. I know she was in the Tag Game in 2000, but I guest that's not the first time they saw her, any idea?
I saw her on the 85 episode of gottsu. Maybe there?