I get it that Raj is Howard’s stooge most of the time. But how in the hell did he get the right card with Penny? :dubious: 
Everybody but Sheldon was in on it.
Wasn’t that at the end of the episode? My understanding is that she would have agreed to any card that he named. I don’t recall that they actually showed her card.
Then why did she ask about it, and why was Howard surprised when she knew the answer? 
Because the joke was on Sheldon and everyone was in on the joke.
Penny probably whispered that Sheldon was a pompous ass and Howard would have looked astonished.
Hmm … maybe.
Yes, Penny was in on it too. Leonard probably clued her in. That whispered conversation with Howard was probably one of the few conversations she had with Howard that she enjoyed.
Howard would have agreed with anything Penny whispered to him to further exasperate Sheldon.
The idea was to knock Sheldon off his high horse. Penny could have said anything, and Howard would have looked astonished and said “That’s right.”
Convenient (25% chance) that Sheldon drew a heart at the end.
Since Raj is Howard’s stooge, I’m sure they had all bases covered in advance. If it hadn’t been a heart, he would have used some other signal.
Maybe? No, that’s exactly what it was. They set up the “we’re going to fuck with Sheldon” plot all episode long - why in the world would they abandon it at the end, where the punchline goes?
Yeah, right. He’s going to win a Nobel Prize.
Penny is a better actress than I thought.