Lionne

There is one line where Penny asks if she picks up a guy, and the guy picks up another girl, and then they all leave the bar together - did she pick up the girl? Bernadette asks her if that really happened, and Penny kinda brushes it off with an implication it might have. Other than that, there is no evidence that Penny has had a large share of 3somes nor ever had a purely lesbian encounter. I think that at first you can tell she likes Amy's compliments (she's particularly pleased when Amy suggests that Penny would fetch a unicorn for her downry) but gets squicked out at other times. The episode with the painting has some great moments in it, but Amy's comments about the sponges and them originally being painted nude is actually one of the jokes which I felt went a little too far. I think whether Penny looked pleased or grossed out is what sold or didn't sell the joke, really, and they had Penny look disturbed too much at Amy's innuendos. I was glad when they ended, personally, but then they got replaced by Amy focusing on her sex life with Sheldon instead. All in all, the picture which has actually been painted for me is that Amy is too inexperienced to know anything about the realities of sex. I thought it was adorable when Sheldon kisses her on the train that she lifts her hands in that whole "oh, I'm being kissed! Hey, I have hands! What do I do with these?!" sort of way that you do when you're inexperienced and young and have never been really kissed before. Amy is more of a talker than a doer - she makes flattering and sometimes inappropriate comments to Penny and Sheldon and worships them (a bit more than she should sometimes), but when things get real she's as awkward and unsure of herself as you would expect.

In season 5, Amy developed a "girl crush" on Penny. Some of her comments were very innocent at first, and really non-sexual, more complimenting Penny's golden hair or flawless skin in a way that suggested Amy kinda worshipped her and was really in awe of being friends with the beautiful, popular girl. The comments got a lot of laughs, though, and then the writers ran with it and made them creepier and more sexually inappropriate. Then the audience stopped laughing at them, and they started to get written out and pretty much suddenly vanished altogether. At Comic Con after the 5th season, the writers were asked about the "gay for Penny" stuff coming out of Amy's mouth, and Steve Molaro looked particularly guilty and said it was a joke which got taken too far and that it got axed fairly quickly when audiences stopped laughing at it. Amy was always meant to be portrayed as having a girl crush on Penny, but moreover, it was supposed to be an extension of the fact that Amy never had any friends in her life (It would seem she was extremely isolated by a very over-protective mother) so when she became "besties" with the very definition of the beautiful, blonde, popular girl, Amy finally felt she fit in somewhere and in some ways let the joy of having real friends for the first time in her life go to her head. It was never meant to suggest that Amy was a lesbian, or bisexual. It's been clear Amy was meant for Sheldon from the get-go, and is heterosexual. (In fact the first time she seemed to have gotten turned on is by Zack.) The writers just got a little loosey-goosey with a joke and then had to reign themselves in later.