I've seen the ep, it's not even a fake reaction to Parsons, Amy is supposed to be turned on by Sheldon rubbing her chest lol
To give a bit more explanation on the episode itself, in the episode she's supposed to be turned on by this, being turned on by rubbing her chest was supposed to be the scene in the show, she's not acting turned on for the purpose of the blooper, this was in the episode. If you watch these bloopers Jim Parsons starts smiling at the situation, she winks at him obviously to make him crack up and he laughs more, then she cracks up too. No tickling at all, just the case of the actors trying to break each other, it's a common blooper