Okay, maybe this is just a “guys don’t get it” thing, but why is she so horrified that everybody at work knows she wears size 10 pants. Was she passing as an 8 or something?

Her reaction seems (to me) more appropriate to Arlo telling her she had a split seam and everybody at work could see her panties all day (even then hiding in the closet now seems odd, but I could chalk that up to artistic license).