Given my panty fetish I would have told her to keep them on so they could soak up my cum after I finished inside her. Well, what are you wearing? Pants, then yes. Skirt or dress, then nope. Or maybe a nice g-string if anything. Would have told her to remove them, and leave them at home. Such a fun distraction during parties. Depends on the skirt really. Might be difficult in the dry cleaners explaining a few stains.X. I would've handed her a pair of vibrating panties, ones you could control whenever you'd like.