Oh no! They're cutting the cake! I told them to wait, but they didn't listen. If you hurry back, they might save a piece."
"Remember when I was all like 'Goodbye.' and you thought you were going to die in that fire? Ya that was fun."
"Please be advised that a taste of blood is not part of any test protocol, but is a side effect of the Aperture Science Material Emancipation grill, which may in semi-rare cases may emancipate dental fillings, crowns, tooth enamel and teeth."
"Well done, remember that the Aperture Science bring your daughter to work day is the perfect time to have her tested."
"Momentum, a function of mass and velocity, is conserved between portals. In Lamon's terms, 'Speedy thing goes in, speedy thing comes out.' -GLaDOs
and everything else! Like her mentioning of Black Mesa.