Used when someone is in a situation where you would expect them to be wearing panties (or equivalent underwear) e.g. under a skirt, dress, or pants, but they aren't.
Removing the no_panties tag. Asuka may not be wearing panties under her plugsuit, but she's not supposed to -- the original series and the Rebuild movies made it a point to show Rei and Asuka weren't wearing panties (or anything else) under their plugsuits.
Not wearing panties under her plugsuit is like not wearing panties under a swimsuit, or not wearing underwear under a kilt. Since it's not something you'd expect them to wear underwear beneath, their lack of underwear shouldn't be tagged.