It says so, right here in your file.
Props if you read the title in PotaDOS.
Just a silly little doodle that was the result of too much time on the WMG's on TV Tropes.
Boo's real name is Chell.
Her constant vanishing act throughout the film shows that she's clearly thinking with portals. Plus, she and Chell look similar.
And then, on one fateful Take-An-Obscure-Relative-To-Work-Day...