Funny idea:
Simon: I'm telling you, Baz plays the violin.
Penny: oh really? You keep making ridiculous accusations. First Baz is a vampire, then he's a violin player, what's next he owns a flower suit?
Simon: *while hitting the table to empathize his point* YES, HE DOES!
Simon: I've already told you that!
Third Person POV:

As Baz's roommate, Simon knew a lot about Baz. From what he smells like, to some of his weird habits, it's safe to say Simon knows Baz better than most. Unfortunately for Simon since he knew the most about Baz at school, that meant people didn't believe what he said about Baz most of the time, even if it was the complete and utter truth.

This particular time that everyone thought Simon was off his rocker for what he says about Baz was at breakfast.
Simon was gorging himself on sour cherry scones, and more butter then is socially acceptable in public, as he was basically eating a stick of butter per scone.
Now the scone eating isn't as important as what Simon is about to say, though it is notable that Baz has been nibbling on a scone as well, though he applies much less butter to it.

The important thing for right now is Simon and Penny's conversation.
Penny let Simon have the figurative floor, as to speak. Simon swallowed the scone that had had shoved into his mouth, and wiped most of the crumbs around his mouth off with his hand, he missed a couple unfortunately.

Simon started to tell Penny about his night, and his homework.
Simon then used that to lead into what he wanted to tell her all morning. "Speaking of stuff I learned, did you know Baz is actually a really good violin player? He's good enough to be a professional, and he can improvise like a boss."

Penny sighed as this wasn't the first time Simon tried to convince her something or another about Baz. She remembered all the times Simon complained about Baz, and then realized that if Simon already used his one a day ticket to talk about Baz then he's going to be going on about Baz ALL day. Thinking of that, something in side of her snapped. If she had to hear one more obviously fake fact about Baz she might kill someone. (She really wants Simon to figure out his crush that he can't see, but is obviously there.)

Because of this she snapped out, "Oh really? You keep making ridiculous accusations. First Baz is a vampire, then he's a violin player, what's next he owns a flower suit?"

Simon fumed at that for a second, before starting on his angry rant, "Yes, he does! I already told you that!" In between every word he hit the table to emphasize his point.

Of course Simon was right. Baz did in fact own a flower suit, a very extra one at that. But as Penny looked at Baz all she could see was the cold, calculating, and collected persona Baz puts out, not the gay mess he is inside, or the over the top person only Simon knows about at Watford.