These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: No Strings Attached
Crosses the Line Twice: The period scene, particularly one line: "It's like there's a crime scene in my pants!"
Fridge Logic: Why do Emma's panties have buttons on the front?
Some kind of fashion?
You can get those fairly easily in the UK. IIRC they were originally a joke item parodying men's pants which then became actually popular for some reason.
Logical extension of boyshorts? Also just happened to be what GAP was carrying at the time of filming.