they're not panties
"They're not panties, so it's not embarrassing!"
A "booster" line in Strike Witches wherein the speaker tells the listeners to forget that their underwear is exposed or treat their underwear as if they are "working" attire, or wearing something over them, probably to put their focus on their job instead.
The line is a self-aware joke about the premise of the series, in which the "witches" - various female pilots of a striker unit combat gear - do not wear anything on their bottom but their panties, which is explained in-universe as to prevent their clothing from tangling with their striker unit.
Possibly said by Miyafuji Yoshika as she wears a school swimsuit underneath her uniform and technically not underwear.