By now we’ve all heard of the famous phrase ‘Julie MacBarfle has cooties!’ writen on Sid’s backpack. Here’s my question: did Julie do something to deserve that phrase (a bully, a spurned love affair, etc.), or is she just an innocent victim of Sid’s nastiness? Discuss!
It’s an in-joke to Julie McDonald, who worked at Pixar during the production of TS.
I realize that; I’m talking about within the context of the film.
Not everything Has a context within the film.
They’re just being imaginative. Maybe Sid actually has a crush on Julie. I don’t know. Haha. It could be anything your heart desires really.
I wouldn’t really call Sid nasty. From a Toy’s point of view I would but as a human he is just a little strange.
Hmm, Hannah might disagree with you there.
He so fancies her. 
I can imagine Sid being quite a sweetheart, underneath that “let’s blow up toys!” exterior.
Yeah, I’ve always interpretted that “I wanna ride the pony!” line as a window into his inner psyche.
Yeah, I’d go far enough to call Sid a flatout juvenile delinquent. As it’s been mentioned, he’s mean to his sister, and very destructive. He also isn’t afraid of breaking other peoples’ property, like at Pizza Planet (there’s also a deleted scene that shows him knocking down a display). Also, those milkcrates are stolen (as stated in an official source), and you also gotta wonder how he got ahold of that road blockade thing he used when he was about to launch Buzz. To top that off, he regularly gets kicked out of summer camp, and he’s just 10.
That’s because they are brother and sister.
LOL, makin’ up a story off the top of my head: There has been some playground bicker/banter between them that has prompted some among their peers to recite that timeless verse, “Sid and Julie, sittin’ in a tree…” Maybe he likes her and is in denial, maybe she likes him and won’t leave him alone, maybe she thinks he has cooties, too. LOL, the possibilities are endless - but there’s some emotion/attention, either good or bad, between them, or he wouldn’t be writing things about her on his backpack. 
I’m playing devil’s advocate here, but maybe he got those items from the back of an abandoned warehouse or some other place of business. Or maybe they weren’t being used and they were given to him. I dunno; just thinking of other possibilities.
Well, I got that from a source that stated that they were stolen. Maybe not all of them, but from a kid with barbed wire around his bed, you never know.
It was just an in-joke to Julie McDonald, one of Pixar’s employees.
As I said to pixarfan9099, I’m aware that it’s an in-joke. The point of this thread is to give the joke context within the film.
I think Sid’s in love!!
But you know, ‘Barfle’ could just be him spoofing her last name. It could be ‘Baffle’.
Yeah, that’s what I thought too.